深度塑性形变对镁合金微观组织和强塑性影响研究
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摘要
密排六方晶体结构的镁合金，由于强度低，塑性差，限制了其结构件上的广泛应用。晶粒细化及合理控制强化相的形态、分布是改善其强塑性的有效途径。转角挤压技术是一种强应变塑性变形技术，可以细化组织，提高性能。目前广泛使用的等径角挤压(ECAP)细化技术由于其成本高，效率低，难以实现工业化。本文提出了一种新型的镁合金强塑性变形技术，就是将挤压比概念引入ECAP技术中形成新型的镁合金复合细化理论技术(UCAP)，实现进一步提高镁合金强塑性的目的。本文以两类代表性镁合金Mg-A1-Zn系(Mg-7.5Al-0.85Zn)、Mg-Zn-Zr-Y系(Mg-6Zn-1.2Y-0.6Zr)合金为研究对象，结合对比ECAP和UCAP挤压技术，采用金相分析、扫描电镜(SEM)、能谱(EDS)分析、X衍射分析(XRD)、差热分析(DSC)、透射电镜(TEM)、Gleeblel500热-力学模拟试验机、力学性能测试等试验手段，系统地研究了镁合金在不同应变速率及不同温度下的流变性能、微观组织及合金的热变形行为以及变形过程中的变形机制，并构建了镁合金材料本构方程，应用Deform-3D塑性有限元软件对镁合金UCAP挤压成形过程中等效应力场、等效应变场和挤压力进行计算机模拟分析，并通过实验验证模拟结果的正确性；同时自行设计制造了带有预热装置的ECAP和UCAP挤压实验模具，研究了铸态及不同道次ECAP态、不同温度UCAP态及UCAP+ECAP二次挤压态镁合金的微观组织，力学性能，揭示了镁合金在强塑性变形过程中的组织演变规律及其力学性能的内在联系，为制备性能优异镁合金提供了详细的实验数据和理论依据，主要研究内容和结论如下：
(1)系统分析和比较了不同变形条件对铸态Mg-7.5Al-0.85Zn和Mg-6Zn-1.2Y-0.6Zr两种镁合金高温单向压缩变形行为的影响。在高温自由压缩过程中，两种合金的流变应力随变形温度和应变速率的不同呈现出不同的形态，且不同程度上表现出了动态再结晶的特征，真应力对温度和应变速率的变化都很敏感，表现为正应变速率敏感材料，各曲线中都是应力随着应变的增大先增大后降低，且在相同应变速率下，应力随着温度的升高而降低，达到峰值应力后试样断裂或流变应力进入稳态阶段；相同变形温度下，材料的峰值应力和稳态应力随应变速率的增大而增大，并分析得到两种镁合金在高温塑性变形时的本构方程，合金元素Y的加入降低镁合金的堆垛层错能，阻碍位错聚集，增加位错高温攀移倾向，使Mg-6Zn-1.2Y-0.6Zr系合金的变形激活能呈现增大的趋势为242KJ/mol，相同条件下铸态Mg-7.5Al-0.85Zn合金变形激活能为181KJ/mol，并采用热加工分析Mg-6Zn-1.2Y-0.6Zr合金的最佳变形条件为温度350℃-400℃，应变速率小于0.05s-1。
(2)铸态Mg-6Zn-1.2Y-0.6Zr镁合金不同热压缩变形条件的组织表现出不连续动态再结晶的特征，低温低变形量小时，出现粗大拉长的变形组织，滑移明显可见，孪生起主导作用，高温时晶粒内部形成了锯齿状特征的几何动态再结晶组织。
(3)利用Deform数值模拟软件对UCAP剪切挤压变形过程中的挤压力和等效应力、等效应变分布分别模拟。结果表明，在所有挤压的参数中起着关键作用的挤压温度和挤压比影响着应力应变的分布和挤压力的大小；在挤压转角处的应力、应变分布最集中，等效应力、等效应变、挤压力随着挤压比的增大而增大，同时挤压力、等效应力随着温度的升高而减小，等效应变随温度的变化不大。整个模拟过程为实际UCAP挤压工艺参数选择提供一定的理论参考价值。
(4)研究分析了ECAP对Mg-7.5Al-0.85Zn合金的微观组织和力学性能的影响变化规律和作用机理。ECAP具有显著的细化晶粒作用，随挤压道次增加，挤压合金的平均晶粒尺寸逐渐减小，尤其在1道次挤压细化能力最强，但组织不太均匀。Mg-7.5Al-0.85Zn合金重熔后原始晶粒尺寸为145μm左右,在温度285℃时实现了无裂纹ECAP挤压。在4道次后的挤压，晶粒基本呈等轴晶，细化均匀性增加，平均晶粒为1.5～3μm，随着挤压道次的继续增加，晶粒粗化，大角度晶界比率增加。细化机制可归结为β相与基体界面处的位错聚集的相溶和ECAP的纯剪切共同导致的动态再结晶机制。β相限制了α-Mg基体的动态再结晶速率，且挤压过程中碎化的β相在α-Mg基体上析出，容易获得细小组织，使Mg-7.5Al-0.85Zn镁合金的组织得到了改善，力学性能得到了提高，拉伸断口形貌由铸态的脆性解理断裂转变为韧性断裂特征。与铸态Mg-7.5Al-0.85Zn镁合金相比，抗拉强度从180MPa提高到306MPa，提高了42%，延伸率由4.7％提高到15.8％，挤压4道次后硬度达到最大值142HL，比铸态Mg-7.5Al-0.85Zn镁合金的硬度91HL提高了36%。
(5)研究分析对比了UCAP对Mg-7.5Al-0.85Zn合金的微观组织和力学性能的影响变化规律和作用机理。UCAP变形挤压只有在1道次的情况下随挤压温度的降低同样具有显著的细化晶粒作用，挤压温度成为UCAP变形过程中最为关键及容易控制的因素，Mg-7.5Al-0.85Zn合金无需重熔可以获得不开裂的UCAP挤压。合金室温合金的室温强塑性得到综合改善。UCAP挤压温度为250℃时平均晶粒尺寸为5.5μm，晶粒变得更加致密细小，抗拉强度为350MPa，延伸率为14%，优于ECAP的四道次挤压。UCAP晶粒变形细化机制归结为墩粗变形过程时引起的晶粒破碎及转角区的纯剪切和挤压变径区破碎和UCAP变形过程中在剪切挤压应力的作用下发生的动态再结晶；位错聚集高能区域产生大量的新晶核，在晶粒内部实现了重排、合并与转动形成新的晶粒，从而促使镁合金得以细化。UCAP+ECAP二次变形由于初始晶粒度差异更能进一步细化晶粒，获得优异的综合性能。
(6) Mg-6Zn-1.2Y-0.6Zr合金的大塑性挤压UCAP又不同于Mg-7.5Al-0.85Zn合金，在UCAP挤压过程中，Mg-6Zn-1.2Y-0.6Zr合金中析出耐高温的硬脆相质点I相和w相，其细化机制为剪切挤压应力的机械剪切机制。基体晶粒也得到了不同程度的细化，在经一次UCAP挤压表现出高的屈服强度和较差的塑性，挤压温度为300℃时平均晶粒尺寸为6.3μm，抗拉强度为290MPa，延伸率为9.1%。在二次挤压过程中，由于晶粒的进一步细化，平均晶粒尺寸达1.5μm第二相粒子弥散分布在Mg-6Zn-1.2Y-0.6Zr合金中，获得抗拉强度为350MPa，延伸率为18%的优异性能。
The application on structure materials of hexagonal close crystal structuremagnesium alloy is limited due to its low ductility and strength. Grainrefinement reasonable control for morphology and distribution of strengtheningphase are effective ways to improve the mechanical properties of the alloy.Angle extrusion technology is a kind of serve plasticity deformation technology,which can refine microstructure and improve mechanical properties. Currentlywidely used equal channel anger pressing refining technology is difficult to beindustrialized due to its high cost and low efficiency. In order to further improvethe strength and toughness of the magnesium alloy, a new type of magnesiumalloy composite extrusion method-unequal channel anger pressing(UCAP)waspresented which organically combined the traditional extrusion and the serveplastic deformation ECAP (equal channel anger pressing). In this study,Mg-7.5Al-0.85Zn and Mg-6Zn-1.2Y-0.6Zr magnesium alloys as serve plasticdeformation materials were processed by ECAP technology and UCAPtechnology to further enhance the strength and plasticity. Microstructureevolution and dynamic recrystallization mechanisms of the as-cast, ECAPed andUCAPed magnesium alloys were studied thoroughly by Optical microscopy(OM), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energyspectrum analysis (EDS), Transmission electron microscopy (TEM) andDifferential scanning calorimetry (DSC). The mechanical properties andmechanism of these magnesium alloys in different conditions were discussed bymechanical test and Gleeble1500thermal simulator. Hot deformation behaviorand deformation mechanism in different strain rate and different temperaturewere systematically studied and the constitutive equation of the two magnesiumalloys was put forward. The extrusion forces, stress and strain distributionduring UCAP processing were investigated by numerical simulation techniques.The correctness of the simulation results through the experimental results wasverified and ECAP and UCAP experiment mold with preheating device weredesigned and manufactured. The relations between microstructure evolution and mechanical properties of the as-cast and ECAPed, UCAPed magnesium alloywere discussed. The main results have been obtained as follows:
1. High temperature compressive deformation behavior under differentdeformation conditions (deformation temperature, strain rate and strain capacity,etc.) of as-cast Mg-7.5Al-0.85Zn and Mg-6Zn-1.2Y-0.6Zr alloy weresystematically analyzed and compared by high temperature compressive testing.Flow stress of two kinds of alloys presented a different form with the differentdeformation temperature and strain rate, and presented a different dynamicrecrystallization characteristic. True stress was very sensitive to the change oftemperature and strain rate, which was the character as the positive strain ratesensitive material. The stress of the curve increased with the increase of strainand then reduced. The maximum value of flow stress and its correspondingstrain value decreased with increasing of deformation temperature or decreasingof strain rate. The constitutive equations of plastic deformation for the twoalloys at elevated temperatures were obtained. The deformationactivation energy of Mg-6Zn-1.2Y-0.6Zr alloy presented the tendency ofincrease to242KJ/mol and to181KJ/mol for as-cast Mg-7.5Al-0.85Zn alloyunder the same condition. The main reason was that elements Y could reduce themagnesium alloy’s stacking energy and hinder the gathered dislocation andincrease climbing tendency of the high temperature dislocation. The optimal hotworking condition was the temperature in the range of350～400℃and strainrate less than0.05s-1.
2. The microstructure observation results of as-cast Mg-6Zn-1.2Y-0.6Zralloy in different deformation condition showed that the deformationmechanisms were mainly discontinuous dynamic recrystallization. Theelongated deformation microstructure in Mg-6Zn-1.2Y-0.6Zr alloy at lowtemperature and small deformation stage appeared; the twin played a leadingrole. The jagged characteristics of geometric dynamic recrystallization wereformed in internal grains; slip dislocation played a key role during hightemperature.
3. The distribution of stress and strain and extrusion force of Mg-6Zn-1.2Y-0.6Zr magnesium alloy during the UCAP process under differenttemperature, strain rate and extrusion ratio were simulated by deform software.Extrusion ratio and extrusion temperature were the key factors in UCAPdeformation process, which controlled actual extrusion pressure and distributionof stress and strain easily.The distribution of stress and strain mostlyconcentrated at the angular of the extrusion dies. The effective stress, effectivestrain and extrusion load became larger as the extrusion ratio. The extrusionforce and effective stress reduced with the increase of extrusion temperature, butthe effective strain had little changes. It was found that the results of simulatedUCAP process could certainly guide the UCAP actual process.
4. The influence on the microstructure and mechanical properties of theECAPed and UCAPed alloys were analyzed and compared. ForMg-7.5Al-0.85Zn magnesium alloy, ECAP had significant grain refinement.With the increasing of number of ECAP passes, mean grains became finer;especially the most effective ECAP pass in the first pass, but the microstructurewas obviously nonuniform. Remelted Mg-7.5Al-0.85Zn alloy with initial grainsize of about145μm can be ECAPed at285℃without crack occurrence. Themost finest mean grain size1.5-3.0μm and the best microstructure uniformitywas obtained after four ECAP passes while grain coarsening occurred after morethan4passes associated with an increase in high angle grain boundary.Grainrefinement mechanism during ECAP can be described as dynamicrecrystallization with combination of the dissolution of the β-Mg17Al12phase atmatrix boundary interface and pure shear stress generated by ECAP. β-Mg17Al12phase inhibited the rate of the dynamic recrystallization and the brokenβ-Mg17Al12phase during ECAP precipitated in the matrix, which led to the finemicrostructure and improved tensile strength and elongation.The fracturemorphology changed from the quasi-cleavage fractures of as-cast alloy todimple-like fracture characteristics. Compared with as-cast Mg-7.5Al-0.85Znalloy, the tensile strength of ECAPed alloys increased by42%, namely, from180MPa to306MPa while the elongation of the ECAPed alloys increased from4.7%to15.8%and the hardness for four passes was the highest value, which was142HL, much higher than91HL of as-cast alloy, which increased by36%.
5. UCAP also has significant refining grain effect with lower temperaturethough only1pass was pressed. Extrusion temperature became the easilycontrolled key factor during UCAP deformation process. Mg-7.5Al-0.85Zn alloycould obtain the non crack UCAPed alloy without remelting. The strength andelongation of Mg-7.5Al-0.85Zn magnesium alloy got improvement as the grainsbecame smaller. When the extrusion temperature was250℃, the average grainsize was4.5μm, strength changed to350MPa, prolongation rate reached14.1%,the strength and toughness of magnesium alloy were more effectively improvedthan ECAPed4passes alloy. Grain refinement mechanism of Mg-7.5Al-0.85Znalloy during UCAP can be described as grain fragmentation in the pure shearstress and extrusion and with the dissolution of the β-Mg17Al12phase at matrixboundary interface and generation by UCAP whole dynamic recrystallization.Under the effect of shear stress, new crystal nucleus can be emerged in theincreased density dislocation high-energy area and then arranged into dislocationboundaries when dislocation continuously moved and nailed up interphase andtransformed to the new grain, therefore the grains could be refined.
6. The effect on the microstructure and mechanical properties of UCAP edMg-6Zn-1.2Y-0.6Zr alloy was different from UCAPed Mg-7.5Al-0.85Zn,Mg-6Zn-1.2Y-0.6Zr alloy grains also had different degree of refinement duringUCAP process, but its refinement mechanism can be described as mechanicalshear mechanism of shear extrusion stress, which was related to the secondphase-high temperature resistant I phase and fragile hard brittle w phasegrain.The tensile tests at room temperature showed lower yield strength andelongation rate to failure of the UCAPed Mg-6Zn-1.2Y-0.6Zr alloy as comparedwith the UCAPed Mg-7.5Al-0.85Zn alloy.The Mg-6Zn-1.2Y-0.6Zr UCAPedalloy showed the cleavage fracture mode, while the fracture surface ofMg-6Zn-1.2Y-0.6Zr UCAP+ECAPed alloy exhibited the some tougheningdimples.The obvious recrystallization occurred in the Mg-6Zn-1.2Y-0.6Zr alloyleads to the large average grain size as well as a number of I phase and W phaseparticles. Tensile tests showed that the Mg-6Zn-1.2Y-0.6Zr alloy exhibits higher yield and ultimate tensile strengths, but lower elongation to failure at roomtemperature. In contrast, the Mg-6Zn-1.2Y-0.6Zr alloy showed higher strengthsand ductility at200℃and300℃, respectively. These differences in the tensilemechanical properties between the two alloys are from the differentcontributions of the strengthening due to the grain refinement and theprecipitation and dispersion strengthening effects generated by the second phaseparticles. The average grain size of the UCAPed+ECAPed Mg-6Zn-1.2Y-0.6Zralloy was finer, which was1.5μm, the second phase particles were dispersed,and performance were obtained with tensile strength of350MPa and theelongation of18%.
(1)系统分析和比较了不同变形条件对铸态Mg-7.5Al-0.85Zn和Mg-6Zn-1.2Y-0.6Zr两种镁合金高温单向压缩变形行为的影响。在高温自由压缩过程中，两种合金的流变应力随变形温度和应变速率的不同呈现出不同的形态，且不同程度上表现出了动态再结晶的特征，真应力对温度和应变速率的变化都很敏感，表现为正应变速率敏感材料，各曲线中都是应力随着应变的增大先增大后降低，且在相同应变速率下，应力随着温度的升高而降低，达到峰值应力后试样断裂或流变应力进入稳态阶段；相同变形温度下，材料的峰值应力和稳态应力随应变速率的增大而增大，并分析得到两种镁合金在高温塑性变形时的本构方程，合金元素Y的加入降低镁合金的堆垛层错能，阻碍位错聚集，增加位错高温攀移倾向，使Mg-6Zn-1.2Y-0.6Zr系合金的变形激活能呈现增大的趋势为242KJ/mol，相同条件下铸态Mg-7.5Al-0.85Zn合金变形激活能为181KJ/mol，并采用热加工分析Mg-6Zn-1.2Y-0.6Zr合金的最佳变形条件为温度350℃-400℃，应变速率小于0.05s-1。
(2)铸态Mg-6Zn-1.2Y-0.6Zr镁合金不同热压缩变形条件的组织表现出不连续动态再结晶的特征，低温低变形量小时，出现粗大拉长的变形组织，滑移明显可见，孪生起主导作用，高温时晶粒内部形成了锯齿状特征的几何动态再结晶组织。
(3)利用Deform数值模拟软件对UCAP剪切挤压变形过程中的挤压力和等效应力、等效应变分布分别模拟。结果表明，在所有挤压的参数中起着关键作用的挤压温度和挤压比影响着应力应变的分布和挤压力的大小；在挤压转角处的应力、应变分布最集中，等效应力、等效应变、挤压力随着挤压比的增大而增大，同时挤压力、等效应力随着温度的升高而减小，等效应变随温度的变化不大。整个模拟过程为实际UCAP挤压工艺参数选择提供一定的理论参考价值。
(4)研究分析了ECAP对Mg-7.5Al-0.85Zn合金的微观组织和力学性能的影响变化规律和作用机理。ECAP具有显著的细化晶粒作用，随挤压道次增加，挤压合金的平均晶粒尺寸逐渐减小，尤其在1道次挤压细化能力最强，但组织不太均匀。Mg-7.5Al-0.85Zn合金重熔后原始晶粒尺寸为145μm左右,在温度285℃时实现了无裂纹ECAP挤压。在4道次后的挤压，晶粒基本呈等轴晶，细化均匀性增加，平均晶粒为1.5～3μm，随着挤压道次的继续增加，晶粒粗化，大角度晶界比率增加。细化机制可归结为β相与基体界面处的位错聚集的相溶和ECAP的纯剪切共同导致的动态再结晶机制。β相限制了α-Mg基体的动态再结晶速率，且挤压过程中碎化的β相在α-Mg基体上析出，容易获得细小组织，使Mg-7.5Al-0.85Zn镁合金的组织得到了改善，力学性能得到了提高，拉伸断口形貌由铸态的脆性解理断裂转变为韧性断裂特征。与铸态Mg-7.5Al-0.85Zn镁合金相比，抗拉强度从180MPa提高到306MPa，提高了42%，延伸率由4.7％提高到15.8％，挤压4道次后硬度达到最大值142HL，比铸态Mg-7.5Al-0.85Zn镁合金的硬度91HL提高了36%。
(5)研究分析对比了UCAP对Mg-7.5Al-0.85Zn合金的微观组织和力学性能的影响变化规律和作用机理。UCAP变形挤压只有在1道次的情况下随挤压温度的降低同样具有显著的细化晶粒作用，挤压温度成为UCAP变形过程中最为关键及容易控制的因素，Mg-7.5Al-0.85Zn合金无需重熔可以获得不开裂的UCAP挤压。合金室温合金的室温强塑性得到综合改善。UCAP挤压温度为250℃时平均晶粒尺寸为5.5μm，晶粒变得更加致密细小，抗拉强度为350MPa，延伸率为14%，优于ECAP的四道次挤压。UCAP晶粒变形细化机制归结为墩粗变形过程时引起的晶粒破碎及转角区的纯剪切和挤压变径区破碎和UCAP变形过程中在剪切挤压应力的作用下发生的动态再结晶；位错聚集高能区域产生大量的新晶核，在晶粒内部实现了重排、合并与转动形成新的晶粒，从而促使镁合金得以细化。UCAP+ECAP二次变形由于初始晶粒度差异更能进一步细化晶粒，获得优异的综合性能。
(6) Mg-6Zn-1.2Y-0.6Zr合金的大塑性挤压UCAP又不同于Mg-7.5Al-0.85Zn合金，在UCAP挤压过程中，Mg-6Zn-1.2Y-0.6Zr合金中析出耐高温的硬脆相质点I相和w相，其细化机制为剪切挤压应力的机械剪切机制。基体晶粒也得到了不同程度的细化，在经一次UCAP挤压表现出高的屈服强度和较差的塑性，挤压温度为300℃时平均晶粒尺寸为6.3μm，抗拉强度为290MPa，延伸率为9.1%。在二次挤压过程中，由于晶粒的进一步细化，平均晶粒尺寸达1.5μm第二相粒子弥散分布在Mg-6Zn-1.2Y-0.6Zr合金中，获得抗拉强度为350MPa，延伸率为18%的优异性能。
The application on structure materials of hexagonal close crystal structuremagnesium alloy is limited due to its low ductility and strength. Grainrefinement reasonable control for morphology and distribution of strengtheningphase are effective ways to improve the mechanical properties of the alloy.Angle extrusion technology is a kind of serve plasticity deformation technology,which can refine microstructure and improve mechanical properties. Currentlywidely used equal channel anger pressing refining technology is difficult to beindustrialized due to its high cost and low efficiency. In order to further improvethe strength and toughness of the magnesium alloy, a new type of magnesiumalloy composite extrusion method-unequal channel anger pressing(UCAP)waspresented which organically combined the traditional extrusion and the serveplastic deformation ECAP (equal channel anger pressing). In this study,Mg-7.5Al-0.85Zn and Mg-6Zn-1.2Y-0.6Zr magnesium alloys as serve plasticdeformation materials were processed by ECAP technology and UCAPtechnology to further enhance the strength and plasticity. Microstructureevolution and dynamic recrystallization mechanisms of the as-cast, ECAPed andUCAPed magnesium alloys were studied thoroughly by Optical microscopy(OM), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energyspectrum analysis (EDS), Transmission electron microscopy (TEM) andDifferential scanning calorimetry (DSC). The mechanical properties andmechanism of these magnesium alloys in different conditions were discussed bymechanical test and Gleeble1500thermal simulator. Hot deformation behaviorand deformation mechanism in different strain rate and different temperaturewere systematically studied and the constitutive equation of the two magnesiumalloys was put forward. The extrusion forces, stress and strain distributionduring UCAP processing were investigated by numerical simulation techniques.The correctness of the simulation results through the experimental results wasverified and ECAP and UCAP experiment mold with preheating device weredesigned and manufactured. The relations between microstructure evolution and mechanical properties of the as-cast and ECAPed, UCAPed magnesium alloywere discussed. The main results have been obtained as follows:
1. High temperature compressive deformation behavior under differentdeformation conditions (deformation temperature, strain rate and strain capacity,etc.) of as-cast Mg-7.5Al-0.85Zn and Mg-6Zn-1.2Y-0.6Zr alloy weresystematically analyzed and compared by high temperature compressive testing.Flow stress of two kinds of alloys presented a different form with the differentdeformation temperature and strain rate, and presented a different dynamicrecrystallization characteristic. True stress was very sensitive to the change oftemperature and strain rate, which was the character as the positive strain ratesensitive material. The stress of the curve increased with the increase of strainand then reduced. The maximum value of flow stress and its correspondingstrain value decreased with increasing of deformation temperature or decreasingof strain rate. The constitutive equations of plastic deformation for the twoalloys at elevated temperatures were obtained. The deformationactivation energy of Mg-6Zn-1.2Y-0.6Zr alloy presented the tendency ofincrease to242KJ/mol and to181KJ/mol for as-cast Mg-7.5Al-0.85Zn alloyunder the same condition. The main reason was that elements Y could reduce themagnesium alloy’s stacking energy and hinder the gathered dislocation andincrease climbing tendency of the high temperature dislocation. The optimal hotworking condition was the temperature in the range of350～400℃and strainrate less than0.05s-1.
2. The microstructure observation results of as-cast Mg-6Zn-1.2Y-0.6Zralloy in different deformation condition showed that the deformationmechanisms were mainly discontinuous dynamic recrystallization. Theelongated deformation microstructure in Mg-6Zn-1.2Y-0.6Zr alloy at lowtemperature and small deformation stage appeared; the twin played a leadingrole. The jagged characteristics of geometric dynamic recrystallization wereformed in internal grains; slip dislocation played a key role during hightemperature.
3. The distribution of stress and strain and extrusion force of Mg-6Zn-1.2Y-0.6Zr magnesium alloy during the UCAP process under differenttemperature, strain rate and extrusion ratio were simulated by deform software.Extrusion ratio and extrusion temperature were the key factors in UCAPdeformation process, which controlled actual extrusion pressure and distributionof stress and strain easily.The distribution of stress and strain mostlyconcentrated at the angular of the extrusion dies. The effective stress, effectivestrain and extrusion load became larger as the extrusion ratio. The extrusionforce and effective stress reduced with the increase of extrusion temperature, butthe effective strain had little changes. It was found that the results of simulatedUCAP process could certainly guide the UCAP actual process.
4. The influence on the microstructure and mechanical properties of theECAPed and UCAPed alloys were analyzed and compared. ForMg-7.5Al-0.85Zn magnesium alloy, ECAP had significant grain refinement.With the increasing of number of ECAP passes, mean grains became finer;especially the most effective ECAP pass in the first pass, but the microstructurewas obviously nonuniform. Remelted Mg-7.5Al-0.85Zn alloy with initial grainsize of about145μm can be ECAPed at285℃without crack occurrence. Themost finest mean grain size1.5-3.0μm and the best microstructure uniformitywas obtained after four ECAP passes while grain coarsening occurred after morethan4passes associated with an increase in high angle grain boundary.Grainrefinement mechanism during ECAP can be described as dynamicrecrystallization with combination of the dissolution of the β-Mg17Al12phase atmatrix boundary interface and pure shear stress generated by ECAP. β-Mg17Al12phase inhibited the rate of the dynamic recrystallization and the brokenβ-Mg17Al12phase during ECAP precipitated in the matrix, which led to the finemicrostructure and improved tensile strength and elongation.The fracturemorphology changed from the quasi-cleavage fractures of as-cast alloy todimple-like fracture characteristics. Compared with as-cast Mg-7.5Al-0.85Znalloy, the tensile strength of ECAPed alloys increased by42%, namely, from180MPa to306MPa while the elongation of the ECAPed alloys increased from4.7%to15.8%and the hardness for four passes was the highest value, which was142HL, much higher than91HL of as-cast alloy, which increased by36%.
5. UCAP also has significant refining grain effect with lower temperaturethough only1pass was pressed. Extrusion temperature became the easilycontrolled key factor during UCAP deformation process. Mg-7.5Al-0.85Zn alloycould obtain the non crack UCAPed alloy without remelting. The strength andelongation of Mg-7.5Al-0.85Zn magnesium alloy got improvement as the grainsbecame smaller. When the extrusion temperature was250℃, the average grainsize was4.5μm, strength changed to350MPa, prolongation rate reached14.1%,the strength and toughness of magnesium alloy were more effectively improvedthan ECAPed4passes alloy. Grain refinement mechanism of Mg-7.5Al-0.85Znalloy during UCAP can be described as grain fragmentation in the pure shearstress and extrusion and with the dissolution of the β-Mg17Al12phase at matrixboundary interface and generation by UCAP whole dynamic recrystallization.Under the effect of shear stress, new crystal nucleus can be emerged in theincreased density dislocation high-energy area and then arranged into dislocationboundaries when dislocation continuously moved and nailed up interphase andtransformed to the new grain, therefore the grains could be refined.
6. The effect on the microstructure and mechanical properties of UCAP edMg-6Zn-1.2Y-0.6Zr alloy was different from UCAPed Mg-7.5Al-0.85Zn,Mg-6Zn-1.2Y-0.6Zr alloy grains also had different degree of refinement duringUCAP process, but its refinement mechanism can be described as mechanicalshear mechanism of shear extrusion stress, which was related to the secondphase-high temperature resistant I phase and fragile hard brittle w phasegrain.The tensile tests at room temperature showed lower yield strength andelongation rate to failure of the UCAPed Mg-6Zn-1.2Y-0.6Zr alloy as comparedwith the UCAPed Mg-7.5Al-0.85Zn alloy.The Mg-6Zn-1.2Y-0.6Zr UCAPedalloy showed the cleavage fracture mode, while the fracture surface ofMg-6Zn-1.2Y-0.6Zr UCAP+ECAPed alloy exhibited the some tougheningdimples.The obvious recrystallization occurred in the Mg-6Zn-1.2Y-0.6Zr alloyleads to the large average grain size as well as a number of I phase and W phaseparticles. Tensile tests showed that the Mg-6Zn-1.2Y-0.6Zr alloy exhibits higher yield and ultimate tensile strengths, but lower elongation to failure at roomtemperature. In contrast, the Mg-6Zn-1.2Y-0.6Zr alloy showed higher strengthsand ductility at200℃and300℃, respectively. These differences in the tensilemechanical properties between the two alloys are from the differentcontributions of the strengthening due to the grain refinement and theprecipitation and dispersion strengthening effects generated by the second phaseparticles. The average grain size of the UCAPed+ECAPed Mg-6Zn-1.2Y-0.6Zralloy was finer, which was1.5μm, the second phase particles were dispersed,and performance were obtained with tensile strength of350MPa and theelongation of18%.
引文
[1]刘静安,盛春磊,王怀国.镁及镁合金的应用及市场发展前景[J].有色金属加工,2007,36(2):1-6.
[2]高超英.年产十万吨镁及镁合金可行性报告[R].山西:山西省化工设计院,2011.
[3]胡斌,等.镁合金在汽车领域中的应用(1)-镁合金在汽车领域中的应用背景和发展状况[J].铸造工程,2007,4:34-35.
[4]袁广银,章晓波,牛佳林,陶海荣.新型可降解生物医用镁合金JDBM的研究进展[J].中国有色金属学报，2011，10.
[5]邓云勇，朱江，李立.新型金属材料镁合金的发展前景分析[J].化工技术经济，2002,(8):9-13.
[6] Lui Hong Wu, Pang Quan Shi, and Mary Lee. The Present Situation and Developmentof Magnesium Industry in China [C]. In IMA-53Program Committee. Japan: Yamaguchi,1996,22-23.
[7] E.Aghion, B.Bronfin. Magnesium Alloys Development Towardsthe21th century [J].Mater. Sci. Forum.2000,(19):350.
[8] Polmar J.Magnesium alloy and applications[J].Materials Science and Technology，1994，10(1)：256-258.
[9] Dwain M.A Global Review of Magnesium Parts in Automobiles[J].Light Metal Age，2006，54(9/10):60-63.
[10] Schumann S, Friedrich H，Current and future use of magnesium in the automobileindustry.Materials Science Forum，2003，419-422:51
[11]陈振华.变形镁合金[M].北京:化学工业出版社,2005.
[12]朱琼，AZ80镁合金微合金化和变形机制研究.[D]北大连理工大学,2012．
[13]丁文江等.镁合金科学与技术[M].北京：科学出版社，2007.
[14]潘复生，韩恩厚.高性能变形镁合金及加工技术[M].北京：化学工业出版社,2005.
[15]肖晓玲,罗承萍,聂建峰,； B.C.Muddle. AZ91Mg-Al合金中β-(Mg17Al12)析出相的形态及其晶体学特征.2001，37:1-7.
[16] Padezhnova EM, Melnik EV, Miliyevskiy RA, Dobatkina TV, Kinzhibalo VV.Investigation of the Mg-Zn-Y System [J]. Russian Meatl (Engl Transl),1982,4:185.
[17] Polmear I J. Magnesium alloys and application [J]. Mater Sci Tech,1994,10:1-14.
[18] Maeng DY, Kim T S, Lee JH, Hong SJ, Seo SK, Chun BS. Microstructure andStrength of Rapidly Solidified and Extruded Mg-Zn alloys [J]. Scripta Materialia,2000,43(5):385-389.
[19] Yi S, Park ES, Ok JB, Kim WT, Kim DH.(Icosahedral phase+Mg) Two PhaseMicrostructures in the Mg-Zn-Y Ternary System [J]. Materials Science and Engineering A,2001,300(1-2):312-315.
[20] Nair KS, Mittal MC, Rare Earths in Magnesium Alloys [J]. Materials Science Forum,1998,30:89-104.
[21]余强国，等.稀土镁合金的发展、应用及开发[J].稀有金属与硬质合金，2006，3:36-38.
[22] Rokhlin LL. Magnesium Alloys Containing Rare earth Metals [M]. London and NewYork: Taylor&Francis Group,2003.
[23] Yuan GY, Liu Y, Ding WJ, Lu C, Effects of Extrusion on The Microstructure andMechanical Properties of Mg-Zn-Gd Alloy Reinforced With Quasicrystalline Particles [J].Materials Science and Engineering A,2008,474:348-354.
[24] Xu DK, Liu L, Xu YB, Han EH, The Micro-mechanism of Fatigue CrackPropagation for a Forged Mg–Zn–Y–Zr Alloy in The Gigacycle Fatigue Regime [J]. Journalof Alloys and Compounds,2008,454(1-2):123-128.
[25]曹富荣,崔建忠,雷方.超轻镁合金的研究历史与发展现状[J].材料工程，1996，9:3-7.
[26] Haferkamp H, Niemeryer M, Boehem R, et al. Development, processing andapplications range of magnesiumLithium alloys [J]. Material Science Forum,2000,31:350-351.
[27]郭旭涛，李培杰，熊玉华，刘树勋，曾大本.稀土在铝、镁合金中的应用[J].材料工程，2004，8：60-64.
[28] Kojima Y. Platform Science and Technology for Advanced Magnesium Alloy [J].Material Science Forum,2000,6:3-7.
[29] Tang YL, DS Zhao, Luo ZP, Shen NF, Zhang SQ. On The Chemical CompositionAnalysis of the Qcosahedral Phase in an Mg-Zn-Y-Zr Ingot [J]. Journal of Alloys andCompounds,1994,204(1-2):17-19.
[30] Buch H' von et al. Development of Mg-Sc-Mn alloys [J]. Materials Science andEngineering A,1999,263:1-7.
[31] Wei LY, Development of Microstructure in Cast Mg-Al-RE Al1oys [J]. MaterialsScience and Technology,1996,9:741-750.
[32]夏翠芹,刘平,任凤章.细晶变形镁合金的研究进展[J].材料导报，2006,20(9)：23-28.
[33]郭学峰.细晶镁合金制备方法及组织与性能[M].北京：冶金工业出版社，2010.
[34] Froes F H, Eliezer D，Aghion E. Proceedings of the second Israeli internationalconference on magnesium science&technology. Dead Sea， Israel：2000:43
[35] Hroyuki Watanabe， Hirosuke Tsutsui， Toshi Mukak． Grain Size Control ofCommercial Wrought Mg-Al-Zn Alloys Utilizing Dynamic Recrystallization[J].Ma terTrans JIM,2001,7:1200.
[36]孟健，佟国栋，张洪杰等.稀土镁中间合金的研究与应用[C].第63届世界镁业大会暨国际镁协2006年年会论文集，2006：38-47.
[37]郭旭涛，李培杰，熊玉华，刘树勋，曾大本.稀土在铝、镁合金中的应用[J].材料工程,2004,8:60-64.
[38]张洪杰，孟健，唐定骧.高性能镁-稀土结构材料的研制、开发与应用[J].中国稀土学报，2004,(22):40-46.
[39]余琨，黎文献，李松瑞等.含稀土镁合金的研究与开发[J].特种铸造及有色合金，2001,(1):41-43.
[40] Luo ZP, Song DY, Zhang SQ, Tang YL, Zhao DS. Effect of Heat-treatment on theStability of the Quasicrystal in a Mg-Zn-Zr-Y Alloy [J]. Materials Letters,1994,21(1):85-88.
[41] Zhao DS, Tang YL, Luo ZP, Shen NF, Wang RH, Zhang SQ. The Face-centeredIcosahedral Quasicrystalline Phase in Mg-Zn-Y-Zr Alloys [J]. Materials Letters,1995,23(4-6):277-281.
[42] Kim IJ, Bae DH, Kim DH, Precipitates in a Mg-Zn-Y Alloy Reinforced by anIcosahedral Quasicrystalline Phase [J]. Materials Science and Engineering A,2003,359:313-318.
[43] Maeng DY, Kim T S, Lee JH, Hong SJ, Seo SK, Chun BS. Microstructure andStrength of Rapidly Solidified and Extruded Mg-Zn alloys [J]. Scripta Materialia,2000,43(5):385-389.
[44] Mabuch M，Kubota K，Higashi I．New recycling process by extrusion for machinedchips of AZ91magnesium and mechanical properties[J]．MaterTrans JIM,1995,36:1249.
[45]梁书锦,王欣,刘祖岩,王尔德. AZ31镁合金不同温度挤压后组织性能研究[J].稀有金属材料与工程,2009,38(7):1276.
[46]石磊等.AZ31镁合金的热挤压变形和力学性能分析[J].锻压技术,2009,34(6):35.
[47]徐春杰,张忠明等.热挤压AZ91D镁合金的组织与力学性能[J].西安理工大学学报,2005,21(4):356.
[48]闫丽媛.热挤压工艺对AZ91D镁合金组织性能的影响[D].山西:中北大学,2009:43.
[49]尹从娟，张星，张治民.热挤压工艺对AZ31镁合金组织性能的影响[J].热加工工艺,2007,36(21):63-64.
[50]李艳辉,李保成,尹从娟.挤压比和挤压温度对AZ31镁合金组织性能的影响[J].技术研究,2008,3:10.
[51]陈彬，林栋樑，曾小勤.等通道角挤压对AZ91镁合金组织性能的影响[J].热加工工艺，2006,35(13):23-27.
[52] Y. Miyahara, Z. Horita, T. G. Langdon. Exceptional super plasticity in an AZ61magnesium alloy processed by extrusion and ECAP [J]. Materials Science and EngineeringA,2006,420:240–244.
[53] Manna R, Agrawal P, Joshi S, Mudda BK, Mukhopadhyay NK, Sastry GVS. ScriptaMater2005;53:1357
[54] Koike J，Ohyama R,Kobayashi T，et a1．Grain boundary sliding in AZ31magnesiumalloy at room tempe rature to523K[J]．Metall Trans，2003，4：445.
[55] Magnesium produced by equal channel angular processing[J].ScriptaMaterialia,2004,50(3):377-381.
[56] Senkov ON, Senkova SV, Scott JM, Miracle DB. Mater Sci Eng2005; A393:12.
[57] Tan J C, Tan M. Superplastic deformation behavior of AZ3l magnesium sheet. TheInternational Workshop on Advance in Materials Science and Technology[C]. SingaporeInstitute of Materials Research&Engineedng, Materials Research Society,2000:173.
[58] Mohri T,Mabuchi M,Asahina T,et al.Microstructural evolution and superplas-ticityof rolled Mg-9Al-1Zn[J].Prog.Mater.Sci,2000,45:103.
[59] Iwahashi Y, Horita Z, Nemoto M, Langdon TG. Acta Mater1998;46:3317.
[60]边丽萍,李线绒,王裕等.等通道转角挤压纯铝的组织演变规律研究[J].电子显微学报,2004,23(4):408.
[61] Shunqi Wang, Wei Liang, Yu Wang, Liping Bian, Kehua Chen. A modified die forequal channel angular pressing [J]. Journal of materials processing technology209(2009)3182
[62] Lee SC, Ha SY, Kim KT, Hwang SM, Huh LM, Chung HS.Finite element analysisfor deformation behavior of an aluminum alloy composite containing SiC particles andporosities during ECAP [J].Mater Sci Eng A2004,371:306–12.
[63] Suo Tao,Li Yulong,Deng Qiong,Liu Yuanyong.Optimal pressing route for continuedequal channel angular pressing by finite element analysis[J].Mater SciEng A2007,466:166–71.
[64] Segal V M, Reznikov V I, Drobyshevskiy A E, et al.Plastic working of metals bysimple shear [J]. Russian Metallurgy,1981,19(1):99-104.
[65]靳丽.等通道角挤压变形镁合金微观组织与力学性能研究[D].上海:上海交通大学,2006:1-2.
[66]郭强,张辉,陈振华等.AZ31镁合金的高温热压缩流变应力行为的研究[J].湘潭大学自然科学学报,2004,26(3):108-111.
[67] Polmear I J. Light Alloys-Metallurgy of the Light Metals [M].3rd edition, Amold,1995,5:153.
[68] M Cabibbo,E Evangelista,V Latini,Thermal stability study on two aluminum alloysProcessed with equal channel angular.pressing[J].Journal of MaterialsScience,2005,39(18):5659-5667.
[69] Watanabe H, Mukai K, Ishikawa K, et al.Low temperature super plasticity of afine-grained ZK60magnesium alloy processed by equal-channel-angular extrusion [J].Scripta Materialia,2002,46(12):815.
[70] LiS,BourkeMAM,etal.Finite element analysis of the plastic deformation zone andworking load in equal channel angular extrusion[J].Mater Sci Eng A,2004,382:217-36.
[71] Valiev RZ, editor.Ultrafine-grained materials prepared by severe plastic deformation[J].Ann des Chim Sci des Mater,996,21:369.
[72] C. Wan et al. Mater. Sci. Eng.2010; A527:2915
[73] OBARA T, YOSHINAGA H, MOROZUMI S.{1122}<1123> Slip system inmagnesium [J]. Acta Metall,1973,21:845-853.
[74] Watanabe H, Mukai K, Ishikawa K, et al.Low temperature super plasticity of afine-grained ZK60magnesium alloy processed by equal-channel-angular extrusion [J].Scripta Materialia,2002,46(12):815.
[75] KOIKE J, KOBAYASHI T, MUKAI T, WATANABE H, SUZUKI M, MARUYAMAK, HIGASHI K. The activity of non-basal slip systems and dynamic recovery at roomtemperature in fine-grained AZ31B magnesium alloys [J]. Acta Materialia,2003,51:2055-2065.
[76] Kojima Y. Platform Science and Technology for Advanced Magnesium Alloy [J].Material Science Forum,2000,6:3-7.
[77] Y.N. Wang et al., Acta Mater2007;55:897
[78] Koike, Metall Mater Trans2005;36A:1689
[79] Yoo M H，AgnewS R，Morris J R，Ho K M. Non-basal slip system in hcp metals andalloys: source mechanisms. Materials Science and Engineering A，2001，319-321：87
[80]李落星，李光耀，钟志华．中、高应变速率下AZ80镁合金高温变形力学行为研究[J]．塑性工程学报，2008，15(12)：96-99．
[81]李保成，王强，张治民．AZ80合金初始晶粒对其流变应力影响的研究[J]．塑性工程学报，2008，15(11)：88-91．
[82] Luo A, Pekguleryuz MO. Cast Magnesium Alloys for Elevated TemperatureApplicatioins [J]. Journal of Materials Science,1994,29(20):5259-5271.
[83] Friedrich H, Schumann S. Research for a new age of magnesium in the automotiveindustry [J]. Journal of Materials Processing Technology,2001,117:276-281.
[84] Kamado S, Kitaguchi Y, Harima Y, Kojima Y, Taniikeand S, Nakatsugava I. HighTemperature Deformation Characteristics and Forgeability of Mg-Heavy Rare EarthElement-Zr Alloys [J]. Journal of Japan Institute of Light Metals,1994,48:168-173.
[85] Hall EO. The Deformation and Ageing of Mild Steel [J]. Proc Phys Soc B,1951,64:747-753.
[86] Valle J A,Pérez-Prado M T,Ruano O A.Deformation mechanisms responsible for thehigh ductility in an Mg AZ31alloy analyzed by electron backscattereddiffraction[J].Metallurgical and Materials Transactions A,2005,36:1427-1438.
[87] CHINO Y, KIMURA K, HAKAMADA M, MABUCHUI M.Mechanical anisotropydue to twinning in an extruded AZ31Mgalloy[J]. Materials Science and Engineering A,2008,485(1/2):311317.
[88] Gao L; Liang SM; Chen RS, et al. Microstructure evolution during reheating ofextruded Mg-Gd-Y-Zr alloy into semisolid state [J]. TRANSACTIONS OFNONFERROUS METALS SOCIETY OF CHINA,2010,20(9):1585-1590.
[89] Wang J, Meng J, Zhang D P, Tang DX, Effect of Y for Enhanced Age HardeningResponse and Mechanical Properties of Mg-Gd-Y-Zr Alloys [J]. Materials Science andEngineering A,2007,456:78-84.
[90] Li, WP; Wang, XM; Zhu, LQ, et al. Formation mechanism of an aluminium-basedchemical conversion coating on AZ91D magnesium alloy [J]. INTERNATIONALJOURNAL OF MINERALS METALLURGY AND MATERIALS,2010,17(5):641-647.
[91] Unsworth WM, King JF, A New Magnesium Al1oys System [J]. Light Metal Age,1979,8:29-32.
[92] NIE JF, MUDDLE BC. Characterisation of strengthening precipitate phases in aMg-Y-Nd alloy [J]. Acta Materialia,2000,48:1691-1703.
[93]刘楚明，刘子娟，朱秀荣，周海涛.镁及镁合金动态再结晶研究进展[J].中国有色金属学报.2006,16(1):1-10.
[94]胡基贵，李落星，莫见虎.AZ31镁合金热挤压变形过程温度变化与控制[J].矿冶工程，2007,27(4):20-25.
[95] I.J.Beyerlein, L.S.Tóth.Progress in Materials Science, Texture evolution inequal-channel angular extrusion [J].2009,54:427–510.
[96] Yang X,Miura H,Sakai T.Dynamic evolution of new grains in magnesium alloyduring hot deformation[J].Mater Trans.2003,419-422:509-514
[97] Hroyuki Watanabe， Hirosuke Tsutsui， Toshi Mukak． Grain Size Control ofCommercial Wrought Mg-Al-Zn Alloys Utilizing Dynamic Recrystallization[J].Ma terTrans JIM，2001，7：1200
[98] Eeiji Ohshimo. Application of Die-cast Magnesium to AVCC [C]. In IMA-53Program Committee. Japan: Yamaguchi,1996.1-16.
[99] Y. Miyahara, Z. Horita, T. G. Langdon. Exceptional super plasticity in an AZ61magnesium alloy processed by extrusion and ECAP [J]. Materials Science and EngineeringA,2006,420:240–244.
[100] Haferkamp H, Niemeryer M, Boehem R, et al. Development, processing andapplications range of magnesiumLithium alloys [J]. Material Science Forum,2000,31:350-351.
[101]吴立鸿，王利国，关绍康．镁合金热变形抗力模型的构建技术．锻压技术，2007，32(4):7-11．
[102]张景怀，唐定骧，张洪杰，等.稀土元素在镁合金中的作用及其应用[J].稀有金属，2008,32(5):659-665．
[103] Li, WP; Wang, XM; Zhu, LQ, et al. Formation mechanism of an aluminium-basedchemical conversion coating on AZ91D magnesium alloy [J]. INTERNATIONALJOURNAL OF MINERALS METALLURGY AND MATERIALS,2010,17(5):641-647.
[104] Wei LY, Development of Microstructure in Cast Mg-Al-RE Al1oys [J]. MaterialsScience and Technology,1996,9:741-750.
[105]张振江.基于DEFORM-3D的液缸锻件成型计算机模拟及其锻造裂纹成因分析[D].重庆:西南交通大学,2008:38.
[106]吴桂敏.AZ31镁合金连续挤压工艺试验及数值模拟[D].大连:大连交通大学,2009:29-30,36.
[107]张水忠.挤压工艺及模具设计[M].化学工业出版社，2009.
[108]]刘祖岩.许玮.王尔德.AZ31镁合金在不同温度场挤压中的数值模拟[J].机械工程材料，2006,30(10):77-87
[109] JIAO Ji-cheng,ZHA O Chuan-ling,SHAO Wei.Study on Modeling and Simulation atNo.3Continuous Caster in Jigging[J],Journal of System Simulation,2007,19(23):5482-5486
[110] Lee SC, Ha SY, Kim KT, Hwang SM, Huh LM, Chung HS.Finite element analysisfor deformation behavior of an aluminum alloy composite containing SiC particles andporosities during ECAP [J].Mater Sci Eng A2004,371:306–12.
[111] Smolyakov Andrey A, Vyacheslav P, et al.Three-dimensional numerical simulationsof multi-pass equal-channel angular pressing by a variation difference method andcomparison with experiment [J].Mater Sci Eng A,2008,493:148–59.
[112] Wang YX, Zeng XQ, Ding WJ. Efect of A14Ti5B Master Alloy on the GrainRefinement of AZ31Magnesium Alloy [J]. Scripta Materialia,2006,54:269-273．
[113] Yang J, Wang LD, Wang LM, Zhang HJ, Microstructures and Mechanical Propertiesof the Mg-4.5Zn-xGd (x=0,2,3,5) Alloys [J]. Journal of Alloys and Compounds,2008,459:274-280.
[114] LiS,BourkeMAM,et al.Finite element analysis of the plastic deformation zone andworking load in equal channel angular extrusion[J].Mater Sci Eng A，2004，382:217-36.
[115]罗治平，张少卿等.稀土在镁合金溶液中作用的热力学分析[J].中国稀土学报，1995,(2):119-122.
[116]唐定骧，孟健，陈云贵等.新型镁稀土合金的研制和应用[J].四川稀土，2003,(2):14-18.
[117] Zhang JH, Niu XD, Qiu X, Liu K, Nan CM, Tang DX, Meng J. Effect ofYttrium-Rich Misch Metal on The Microstructures, Mechanical Properties and CorrosionBehavior of Die Cast AZ91alloy [J]. Journal of Alloys and Compounds,2009,471:322-330.
[118] Gao L; Liang SM; Chen RS, et al. Microstructure evolution during reheating ofextruded Mg-Gd-Y-Zr alloy into semisolid state [J]. TRANSACTIONS OFNONFERROUS METALS SOCIETY OF CHINA,2010,20(9):1585-1590.
[119] Wang J, Meng J, Zhang D P, Tang DX, Effect of Y for Enhanced Age HardeningResponse and Mechanical Properties of Mg-Gd-Y-Zr Alloys [J]. Materials Science andEngineering A,2007,456:78-84.
[120] T.E. Leontix. The properties of sand cast Mg-RE alloys [J]. Trans. AIME,1949,191:257-269.
[121] R.J.M. Payne, N. Bailey. Improvement of the age hardening properties of MG-REalloys by addition of Ag [J]. J. Inst. Met,1959-1960,88:417-427.
[122]张洪杰，孟健，唐定骧.高性能镁-稀土结构材料的研制、开发与应用[J].中国稀土学报，2004,(22):40-46.
[123]陈振华.耐热镁合金[M].北京：化学工业出版社，2007.
[124]余强国，等.稀土镁合金的发展、应用及开发[J].稀有金属与硬质合金，2006，3:36-38.
[125] Rokhlin LL. Magnesium Alloys Containing Rare earth Metals [M]. London and NewYork: Taylor&Francis Group,2003.
[126] Iwasawa S, Negishi Y, Kamado S, Kojima Y, Ninomiy R, Age HardeningCharacteristics and High Temperature Tensile Properties of Mg-Gd and Mg-Dy alloys [J].Journal of Japan Institute of Light Metals,1994,44:3-8.
[127] Kamado S, Iwasawa S, Ohuchi K, Kojima Y, Ninomiy R, Age HardeningCharacteristics and High Temperature Tensile Properties of Mg-Gd and Mg-Dy Alloys [J].Journal of Japan Institute of Light Metals,1994,42:727-733.
[128]孟健，佟国栋，张洪杰等.稀土镁中间合金的研究与应用[C].第63届世界镁业大会暨国际镁协2006年年会论文集，2006：38-47.
[129] I.P. Moreno, T.K. Nandy, J.W. Jones, J.E. Allison, T.M. Pollock. Microstructuralstability and creep of rare-earth containing magnesium alloys [J]. Scripta Materialia,2003,48:1029-1034.
[130] Ben-Hamu, G; Eliezer, D; Shin, KS. The Relation between Microstructure andCorrosion Behavior of New Mg-Al-X Alloys for Transportation Application [J].CORROSION, PROCESSES AND ADVANCED MATERIALS IN INDUSTRY,2010,(95):43-46.
[131] Garboggini A, Mcshane HB. Effect of Zn and Si Additions on Structure andProperties of Rapidly Solidified Mg-Al alloys [J]. Materials Science and Technology,1994,9:763-769.
[132] Srinivasan, A; Pillai, UTS; Pai, BC. Effects of elemental additions (Si and Sb) on theageing behavior of AZ91magnesium alloy [J]. MATERIALS SCIENCE ANDENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTUREAND PROCESSING,2010,527(24-25):6543-6550.
[133] Polmear I J. Magnesium alloys and application [J]. Mater Sci Tech,1994,10:1-14.
[134] Padezhnova EM, Melnik EV, Miliyevskiy RA, Dobatkina TV, Kinzhibalo VV.Investigation of the Mg-Zn-Y System [J]. Russian Meatl (Engl Transl),1982,4:185.
[135] Zhang, P; Lindemann, J; Ding, WJ, et al. Effect of roller burnishing on fatigueproperties of the hot-rolled Mg-12Gd-3Y magnesium alloy [J]. MATERIALS CHEMISTRYAND PHYSICS,2010,124(1):835-840.
[136] Nair KS, Mittal MC, Rare Earths in Magnesium Alloys [J]. Materials Science Forum,1998,30:89-104.
[137] Petterson G, Westengen H, Hoier R, Lohne O. Microstructure of A Pressure Die CastMagnesium-4wt.%Aluminium Alloy Modified with Rare Earth Additions [J]. MaterialsScience and Engineering A,1996,207(1):115-120.
[138] Yi S, Park ES, Ok JB, Kim WT, Kim DH.(Icosahedral phase+Mg) Two PhaseMicrostructures in the Mg-Zn-Y Ternary System [J]. Materials Science and Engineering A,2001,300(1-2):312-315.
[139] Yoshida T, Itoh K, Tamura R, Takeuchi S. Plastic Deformation and Hardness inMg–Zn–(Y, Ho) Icosahedral Quasicrystals [J]. Materials Science and Engineering A,2000,294-296:786-789.
[140] Zhao DS, Tang YL, Luo ZP, Shen NF, Wang RH, Zhang SQ. The Face-centeredIcosahedral Quasicrystalline Phase in Mg-Zn-Y-Zr Alloys [J]. Materials Letters,1995,23(4-6):277-281.
[141] Luo ZP, Zhang SQ, Tang YL, Zhao DS. On the Stable Quasicrystals in SlowlyCooled Mg-Zn-Y Alloys [J]. Scripta Metallurgica and Materialia,1995,32:1411-1416.
[142] Tang YL, DS Zhao, Luo ZP, Shen NF, Zhang SQ. On The Chemical CompositionAnalysis of the Qcosahedral Phase in an Mg-Zn-Y-Zr Ingot [J]. Journal of Alloys andCompounds,1994,204(1-2):17-19.
[143] Yuan GY, Liu Y, Ding WJ, Lu C, Effects of Extrusion on The Microstructure andMechanical Properties of Mg-Zn-Gd Alloy Reinforced With Quasicrystalline Particles [J].Materials Science and Engineering A,2008,474:348-354.
[144] Kamado S, Ashie T, Ohshima Y. Tensile Properties Andformability of Mg-Ligrain-refined ECAP process [J]. Mater Sci Forum,2000,350-351:55-62.
[145] Decker R F.The Renaissance in Magnesium [J].Advanced Materials&Processes，2004，154(3)：31-33.
[146] I. P. Moreno, T. K. Nandy, J. W. Jones, J. E. Allison, T. M. Pollock. Microstructuralcharacterization of a die-cast magnesium-rare earth alloy [J]. Scripta Materialia,2001,(45):1423-1439.
[147] L. Y. Wei, G. L. Dunlop, H. Westengen. Precipitation hardening of Mg-Zn andMg-Zn-RE alloys [J]. Metall. Mater. Trans. A,1995,(26):1705-1706.
[148] Qi-chi LE, Zhi-qiang ZHANG, Zhi-wen SHAO, Jian-zhong CUI, Yi XIE.Microstructures and mechanical properties of Mg-2%Zn-0.4%RE alloys [J]. Transactions ofNonferrous Metals Society of China,2010,20:352-356.
[149] H. Yao, Y. Li, A. T. S. Wee. Passivity behavior of melt-spun Mg-Y alloys.Electrochimica Acta,2003,(48):4197-4204.
[150] O. Fruhwirth, G. W. Herzog, I. Hollerer, A. Rachetti. Dissolution and hydrationkinetics of MgO [J]. Surf. Technol.,1985,(24):301-317.
[151] MORDIKE BL, EBERT T. Magnesium: properties-applications-potential [J].Materials Science and Engineering A,2001,302(11):37-45.
[152] ANTION C, DONNADIEU P, PERRARD F, DESCHAMPS A, TASSIN C. PISCH A.Hardening precipitation in a Mg-5Y-3RE alloy [J]. Acta Materialia,2003,51:5335-5348.
[153] APPS PJ, KARIMZADEH H, KING JF, LORIMER GW. Precipitation reactions inMagnesium-rare earth alloys containing Yttrium, Gadolinium or Dysprosium [J]. ScriptaMaterialia,2003,48:1023-1028.
[154] P. Mengucci. Structure evolution of a WE43Mg alloy submitted to different thermaltreatments [J]. Materials Science and Engineering A,2008,479:37-44.
[155] PING DH, HONO K, NIE JF. Atom probe characterization of plate-like precipitatesin a Mg-RE-Zn-Zr casting alloy [J]. Scripta Materialia,2003,48:1017-1022.
[2]高超英.年产十万吨镁及镁合金可行性报告[R].山西:山西省化工设计院,2011.
[3]胡斌,等.镁合金在汽车领域中的应用(1)-镁合金在汽车领域中的应用背景和发展状况[J].铸造工程,2007,4:34-35.
[4]袁广银,章晓波,牛佳林,陶海荣.新型可降解生物医用镁合金JDBM的研究进展[J].中国有色金属学报，2011，10.
[5]邓云勇，朱江，李立.新型金属材料镁合金的发展前景分析[J].化工技术经济，2002,(8):9-13.
[6] Lui Hong Wu, Pang Quan Shi, and Mary Lee. The Present Situation and Developmentof Magnesium Industry in China [C]. In IMA-53Program Committee. Japan: Yamaguchi,1996,22-23.
[7] E.Aghion, B.Bronfin. Magnesium Alloys Development Towardsthe21th century [J].Mater. Sci. Forum.2000,(19):350.
[8] Polmar J.Magnesium alloy and applications[J].Materials Science and Technology，1994，10(1)：256-258.
[9] Dwain M.A Global Review of Magnesium Parts in Automobiles[J].Light Metal Age，2006，54(9/10):60-63.
[10] Schumann S, Friedrich H，Current and future use of magnesium in the automobileindustry.Materials Science Forum，2003，419-422:51
[11]陈振华.变形镁合金[M].北京:化学工业出版社,2005.
[12]朱琼，AZ80镁合金微合金化和变形机制研究.[D]北大连理工大学,2012．
[13]丁文江等.镁合金科学与技术[M].北京：科学出版社，2007.
[14]潘复生，韩恩厚.高性能变形镁合金及加工技术[M].北京：化学工业出版社,2005.
[15]肖晓玲,罗承萍,聂建峰,； B.C.Muddle. AZ91Mg-Al合金中β-(Mg17Al12)析出相的形态及其晶体学特征.2001，37:1-7.
[16] Padezhnova EM, Melnik EV, Miliyevskiy RA, Dobatkina TV, Kinzhibalo VV.Investigation of the Mg-Zn-Y System [J]. Russian Meatl (Engl Transl),1982,4:185.
[17] Polmear I J. Magnesium alloys and application [J]. Mater Sci Tech,1994,10:1-14.
[18] Maeng DY, Kim T S, Lee JH, Hong SJ, Seo SK, Chun BS. Microstructure andStrength of Rapidly Solidified and Extruded Mg-Zn alloys [J]. Scripta Materialia,2000,43(5):385-389.
[19] Yi S, Park ES, Ok JB, Kim WT, Kim DH.(Icosahedral phase+Mg) Two PhaseMicrostructures in the Mg-Zn-Y Ternary System [J]. Materials Science and Engineering A,2001,300(1-2):312-315.
[20] Nair KS, Mittal MC, Rare Earths in Magnesium Alloys [J]. Materials Science Forum,1998,30:89-104.
[21]余强国，等.稀土镁合金的发展、应用及开发[J].稀有金属与硬质合金，2006，3:36-38.
[22] Rokhlin LL. Magnesium Alloys Containing Rare earth Metals [M]. London and NewYork: Taylor&Francis Group,2003.
[23] Yuan GY, Liu Y, Ding WJ, Lu C, Effects of Extrusion on The Microstructure andMechanical Properties of Mg-Zn-Gd Alloy Reinforced With Quasicrystalline Particles [J].Materials Science and Engineering A,2008,474:348-354.
[24] Xu DK, Liu L, Xu YB, Han EH, The Micro-mechanism of Fatigue CrackPropagation for a Forged Mg–Zn–Y–Zr Alloy in The Gigacycle Fatigue Regime [J]. Journalof Alloys and Compounds,2008,454(1-2):123-128.
[25]曹富荣,崔建忠,雷方.超轻镁合金的研究历史与发展现状[J].材料工程，1996，9:3-7.
[26] Haferkamp H, Niemeryer M, Boehem R, et al. Development, processing andapplications range of magnesiumLithium alloys [J]. Material Science Forum,2000,31:350-351.
[27]郭旭涛，李培杰，熊玉华，刘树勋，曾大本.稀土在铝、镁合金中的应用[J].材料工程，2004，8：60-64.
[28] Kojima Y. Platform Science and Technology for Advanced Magnesium Alloy [J].Material Science Forum,2000,6:3-7.
[29] Tang YL, DS Zhao, Luo ZP, Shen NF, Zhang SQ. On The Chemical CompositionAnalysis of the Qcosahedral Phase in an Mg-Zn-Y-Zr Ingot [J]. Journal of Alloys andCompounds,1994,204(1-2):17-19.
[30] Buch H' von et al. Development of Mg-Sc-Mn alloys [J]. Materials Science andEngineering A,1999,263:1-7.
[31] Wei LY, Development of Microstructure in Cast Mg-Al-RE Al1oys [J]. MaterialsScience and Technology,1996,9:741-750.
[32]夏翠芹,刘平,任凤章.细晶变形镁合金的研究进展[J].材料导报，2006,20(9)：23-28.
[33]郭学峰.细晶镁合金制备方法及组织与性能[M].北京：冶金工业出版社，2010.
[34] Froes F H, Eliezer D，Aghion E. Proceedings of the second Israeli internationalconference on magnesium science&technology. Dead Sea， Israel：2000:43
[35] Hroyuki Watanabe， Hirosuke Tsutsui， Toshi Mukak． Grain Size Control ofCommercial Wrought Mg-Al-Zn Alloys Utilizing Dynamic Recrystallization[J].Ma terTrans JIM,2001,7:1200.
[36]孟健，佟国栋，张洪杰等.稀土镁中间合金的研究与应用[C].第63届世界镁业大会暨国际镁协2006年年会论文集，2006：38-47.
[37]郭旭涛，李培杰，熊玉华，刘树勋，曾大本.稀土在铝、镁合金中的应用[J].材料工程,2004,8:60-64.
[38]张洪杰，孟健，唐定骧.高性能镁-稀土结构材料的研制、开发与应用[J].中国稀土学报，2004,(22):40-46.
[39]余琨，黎文献，李松瑞等.含稀土镁合金的研究与开发[J].特种铸造及有色合金，2001,(1):41-43.
[40] Luo ZP, Song DY, Zhang SQ, Tang YL, Zhao DS. Effect of Heat-treatment on theStability of the Quasicrystal in a Mg-Zn-Zr-Y Alloy [J]. Materials Letters,1994,21(1):85-88.
[41] Zhao DS, Tang YL, Luo ZP, Shen NF, Wang RH, Zhang SQ. The Face-centeredIcosahedral Quasicrystalline Phase in Mg-Zn-Y-Zr Alloys [J]. Materials Letters,1995,23(4-6):277-281.
[42] Kim IJ, Bae DH, Kim DH, Precipitates in a Mg-Zn-Y Alloy Reinforced by anIcosahedral Quasicrystalline Phase [J]. Materials Science and Engineering A,2003,359:313-318.
[43] Maeng DY, Kim T S, Lee JH, Hong SJ, Seo SK, Chun BS. Microstructure andStrength of Rapidly Solidified and Extruded Mg-Zn alloys [J]. Scripta Materialia,2000,43(5):385-389.
[44] Mabuch M，Kubota K，Higashi I．New recycling process by extrusion for machinedchips of AZ91magnesium and mechanical properties[J]．MaterTrans JIM,1995,36:1249.
[45]梁书锦,王欣,刘祖岩,王尔德. AZ31镁合金不同温度挤压后组织性能研究[J].稀有金属材料与工程,2009,38(7):1276.
[46]石磊等.AZ31镁合金的热挤压变形和力学性能分析[J].锻压技术,2009,34(6):35.
[47]徐春杰,张忠明等.热挤压AZ91D镁合金的组织与力学性能[J].西安理工大学学报,2005,21(4):356.
[48]闫丽媛.热挤压工艺对AZ91D镁合金组织性能的影响[D].山西:中北大学,2009:43.
[49]尹从娟，张星，张治民.热挤压工艺对AZ31镁合金组织性能的影响[J].热加工工艺,2007,36(21):63-64.
[50]李艳辉,李保成,尹从娟.挤压比和挤压温度对AZ31镁合金组织性能的影响[J].技术研究,2008,3:10.
[51]陈彬，林栋樑，曾小勤.等通道角挤压对AZ91镁合金组织性能的影响[J].热加工工艺，2006,35(13):23-27.
[52] Y. Miyahara, Z. Horita, T. G. Langdon. Exceptional super plasticity in an AZ61magnesium alloy processed by extrusion and ECAP [J]. Materials Science and EngineeringA,2006,420:240–244.
[53] Manna R, Agrawal P, Joshi S, Mudda BK, Mukhopadhyay NK, Sastry GVS. ScriptaMater2005;53:1357
[54] Koike J，Ohyama R,Kobayashi T，et a1．Grain boundary sliding in AZ31magnesiumalloy at room tempe rature to523K[J]．Metall Trans，2003，4：445.
[55] Magnesium produced by equal channel angular processing[J].ScriptaMaterialia,2004,50(3):377-381.
[56] Senkov ON, Senkova SV, Scott JM, Miracle DB. Mater Sci Eng2005; A393:12.
[57] Tan J C, Tan M. Superplastic deformation behavior of AZ3l magnesium sheet. TheInternational Workshop on Advance in Materials Science and Technology[C]. SingaporeInstitute of Materials Research&Engineedng, Materials Research Society,2000:173.
[58] Mohri T,Mabuchi M,Asahina T,et al.Microstructural evolution and superplas-ticityof rolled Mg-9Al-1Zn[J].Prog.Mater.Sci,2000,45:103.
[59] Iwahashi Y, Horita Z, Nemoto M, Langdon TG. Acta Mater1998;46:3317.
[60]边丽萍,李线绒,王裕等.等通道转角挤压纯铝的组织演变规律研究[J].电子显微学报,2004,23(4):408.
[61] Shunqi Wang, Wei Liang, Yu Wang, Liping Bian, Kehua Chen. A modified die forequal channel angular pressing [J]. Journal of materials processing technology209(2009)3182
[62] Lee SC, Ha SY, Kim KT, Hwang SM, Huh LM, Chung HS.Finite element analysisfor deformation behavior of an aluminum alloy composite containing SiC particles andporosities during ECAP [J].Mater Sci Eng A2004,371:306–12.
[63] Suo Tao,Li Yulong,Deng Qiong,Liu Yuanyong.Optimal pressing route for continuedequal channel angular pressing by finite element analysis[J].Mater SciEng A2007,466:166–71.
[64] Segal V M, Reznikov V I, Drobyshevskiy A E, et al.Plastic working of metals bysimple shear [J]. Russian Metallurgy,1981,19(1):99-104.
[65]靳丽.等通道角挤压变形镁合金微观组织与力学性能研究[D].上海:上海交通大学,2006:1-2.
[66]郭强,张辉,陈振华等.AZ31镁合金的高温热压缩流变应力行为的研究[J].湘潭大学自然科学学报,2004,26(3):108-111.
[67] Polmear I J. Light Alloys-Metallurgy of the Light Metals [M].3rd edition, Amold,1995,5:153.
[68] M Cabibbo,E Evangelista,V Latini,Thermal stability study on two aluminum alloysProcessed with equal channel angular.pressing[J].Journal of MaterialsScience,2005,39(18):5659-5667.
[69] Watanabe H, Mukai K, Ishikawa K, et al.Low temperature super plasticity of afine-grained ZK60magnesium alloy processed by equal-channel-angular extrusion [J].Scripta Materialia,2002,46(12):815.
[70] LiS,BourkeMAM,etal.Finite element analysis of the plastic deformation zone andworking load in equal channel angular extrusion[J].Mater Sci Eng A,2004,382:217-36.
[71] Valiev RZ, editor.Ultrafine-grained materials prepared by severe plastic deformation[J].Ann des Chim Sci des Mater,996,21:369.
[72] C. Wan et al. Mater. Sci. Eng.2010; A527:2915
[73] OBARA T, YOSHINAGA H, MOROZUMI S.{1122}<1123> Slip system inmagnesium [J]. Acta Metall,1973,21:845-853.
[74] Watanabe H, Mukai K, Ishikawa K, et al.Low temperature super plasticity of afine-grained ZK60magnesium alloy processed by equal-channel-angular extrusion [J].Scripta Materialia,2002,46(12):815.
[75] KOIKE J, KOBAYASHI T, MUKAI T, WATANABE H, SUZUKI M, MARUYAMAK, HIGASHI K. The activity of non-basal slip systems and dynamic recovery at roomtemperature in fine-grained AZ31B magnesium alloys [J]. Acta Materialia,2003,51:2055-2065.
[76] Kojima Y. Platform Science and Technology for Advanced Magnesium Alloy [J].Material Science Forum,2000,6:3-7.
[77] Y.N. Wang et al., Acta Mater2007;55:897
[78] Koike, Metall Mater Trans2005;36A:1689
[79] Yoo M H，AgnewS R，Morris J R，Ho K M. Non-basal slip system in hcp metals andalloys: source mechanisms. Materials Science and Engineering A，2001，319-321：87
[80]李落星，李光耀，钟志华．中、高应变速率下AZ80镁合金高温变形力学行为研究[J]．塑性工程学报，2008，15(12)：96-99．
[81]李保成，王强，张治民．AZ80合金初始晶粒对其流变应力影响的研究[J]．塑性工程学报，2008，15(11)：88-91．
[82] Luo A, Pekguleryuz MO. Cast Magnesium Alloys for Elevated TemperatureApplicatioins [J]. Journal of Materials Science,1994,29(20):5259-5271.
[83] Friedrich H, Schumann S. Research for a new age of magnesium in the automotiveindustry [J]. Journal of Materials Processing Technology,2001,117:276-281.
[84] Kamado S, Kitaguchi Y, Harima Y, Kojima Y, Taniikeand S, Nakatsugava I. HighTemperature Deformation Characteristics and Forgeability of Mg-Heavy Rare EarthElement-Zr Alloys [J]. Journal of Japan Institute of Light Metals,1994,48:168-173.
[85] Hall EO. The Deformation and Ageing of Mild Steel [J]. Proc Phys Soc B,1951,64:747-753.
[86] Valle J A,Pérez-Prado M T,Ruano O A.Deformation mechanisms responsible for thehigh ductility in an Mg AZ31alloy analyzed by electron backscattereddiffraction[J].Metallurgical and Materials Transactions A,2005,36:1427-1438.
[87] CHINO Y, KIMURA K, HAKAMADA M, MABUCHUI M.Mechanical anisotropydue to twinning in an extruded AZ31Mgalloy[J]. Materials Science and Engineering A,2008,485(1/2):311317.
[88] Gao L; Liang SM; Chen RS, et al. Microstructure evolution during reheating ofextruded Mg-Gd-Y-Zr alloy into semisolid state [J]. TRANSACTIONS OFNONFERROUS METALS SOCIETY OF CHINA,2010,20(9):1585-1590.
[89] Wang J, Meng J, Zhang D P, Tang DX, Effect of Y for Enhanced Age HardeningResponse and Mechanical Properties of Mg-Gd-Y-Zr Alloys [J]. Materials Science andEngineering A,2007,456:78-84.
[90] Li, WP; Wang, XM; Zhu, LQ, et al. Formation mechanism of an aluminium-basedchemical conversion coating on AZ91D magnesium alloy [J]. INTERNATIONALJOURNAL OF MINERALS METALLURGY AND MATERIALS,2010,17(5):641-647.
[91] Unsworth WM, King JF, A New Magnesium Al1oys System [J]. Light Metal Age,1979,8:29-32.
[92] NIE JF, MUDDLE BC. Characterisation of strengthening precipitate phases in aMg-Y-Nd alloy [J]. Acta Materialia,2000,48:1691-1703.
[93]刘楚明，刘子娟，朱秀荣，周海涛.镁及镁合金动态再结晶研究进展[J].中国有色金属学报.2006,16(1):1-10.
[94]胡基贵，李落星，莫见虎.AZ31镁合金热挤压变形过程温度变化与控制[J].矿冶工程，2007,27(4):20-25.
[95] I.J.Beyerlein, L.S.Tóth.Progress in Materials Science, Texture evolution inequal-channel angular extrusion [J].2009,54:427–510.
[96] Yang X,Miura H,Sakai T.Dynamic evolution of new grains in magnesium alloyduring hot deformation[J].Mater Trans.2003,419-422:509-514
[97] Hroyuki Watanabe， Hirosuke Tsutsui， Toshi Mukak． Grain Size Control ofCommercial Wrought Mg-Al-Zn Alloys Utilizing Dynamic Recrystallization[J].Ma terTrans JIM，2001，7：1200
[98] Eeiji Ohshimo. Application of Die-cast Magnesium to AVCC [C]. In IMA-53Program Committee. Japan: Yamaguchi,1996.1-16.
[99] Y. Miyahara, Z. Horita, T. G. Langdon. Exceptional super plasticity in an AZ61magnesium alloy processed by extrusion and ECAP [J]. Materials Science and EngineeringA,2006,420:240–244.
[100] Haferkamp H, Niemeryer M, Boehem R, et al. Development, processing andapplications range of magnesiumLithium alloys [J]. Material Science Forum,2000,31:350-351.
[101]吴立鸿，王利国，关绍康．镁合金热变形抗力模型的构建技术．锻压技术，2007，32(4):7-11．
[102]张景怀，唐定骧，张洪杰，等.稀土元素在镁合金中的作用及其应用[J].稀有金属，2008,32(5):659-665．
[103] Li, WP; Wang, XM; Zhu, LQ, et al. Formation mechanism of an aluminium-basedchemical conversion coating on AZ91D magnesium alloy [J]. INTERNATIONALJOURNAL OF MINERALS METALLURGY AND MATERIALS,2010,17(5):641-647.
[104] Wei LY, Development of Microstructure in Cast Mg-Al-RE Al1oys [J]. MaterialsScience and Technology,1996,9:741-750.
[105]张振江.基于DEFORM-3D的液缸锻件成型计算机模拟及其锻造裂纹成因分析[D].重庆:西南交通大学,2008:38.
[106]吴桂敏.AZ31镁合金连续挤压工艺试验及数值模拟[D].大连:大连交通大学,2009:29-30,36.
[107]张水忠.挤压工艺及模具设计[M].化学工业出版社，2009.
[108]]刘祖岩.许玮.王尔德.AZ31镁合金在不同温度场挤压中的数值模拟[J].机械工程材料，2006,30(10):77-87
[109] JIAO Ji-cheng,ZHA O Chuan-ling,SHAO Wei.Study on Modeling and Simulation atNo.3Continuous Caster in Jigging[J],Journal of System Simulation,2007,19(23):5482-5486
[110] Lee SC, Ha SY, Kim KT, Hwang SM, Huh LM, Chung HS.Finite element analysisfor deformation behavior of an aluminum alloy composite containing SiC particles andporosities during ECAP [J].Mater Sci Eng A2004,371:306–12.
[111] Smolyakov Andrey A, Vyacheslav P, et al.Three-dimensional numerical simulationsof multi-pass equal-channel angular pressing by a variation difference method andcomparison with experiment [J].Mater Sci Eng A,2008,493:148–59.
[112] Wang YX, Zeng XQ, Ding WJ. Efect of A14Ti5B Master Alloy on the GrainRefinement of AZ31Magnesium Alloy [J]. Scripta Materialia,2006,54:269-273．
[113] Yang J, Wang LD, Wang LM, Zhang HJ, Microstructures and Mechanical Propertiesof the Mg-4.5Zn-xGd (x=0,2,3,5) Alloys [J]. Journal of Alloys and Compounds,2008,459:274-280.
[114] LiS,BourkeMAM,et al.Finite element analysis of the plastic deformation zone andworking load in equal channel angular extrusion[J].Mater Sci Eng A，2004，382:217-36.
[115]罗治平，张少卿等.稀土在镁合金溶液中作用的热力学分析[J].中国稀土学报，1995,(2):119-122.
[116]唐定骧，孟健，陈云贵等.新型镁稀土合金的研制和应用[J].四川稀土，2003,(2):14-18.
[117] Zhang JH, Niu XD, Qiu X, Liu K, Nan CM, Tang DX, Meng J. Effect ofYttrium-Rich Misch Metal on The Microstructures, Mechanical Properties and CorrosionBehavior of Die Cast AZ91alloy [J]. Journal of Alloys and Compounds,2009,471:322-330.
[118] Gao L; Liang SM; Chen RS, et al. Microstructure evolution during reheating ofextruded Mg-Gd-Y-Zr alloy into semisolid state [J]. TRANSACTIONS OFNONFERROUS METALS SOCIETY OF CHINA,2010,20(9):1585-1590.
[119] Wang J, Meng J, Zhang D P, Tang DX, Effect of Y for Enhanced Age HardeningResponse and Mechanical Properties of Mg-Gd-Y-Zr Alloys [J]. Materials Science andEngineering A,2007,456:78-84.
[120] T.E. Leontix. The properties of sand cast Mg-RE alloys [J]. Trans. AIME,1949,191:257-269.
[121] R.J.M. Payne, N. Bailey. Improvement of the age hardening properties of MG-REalloys by addition of Ag [J]. J. Inst. Met,1959-1960,88:417-427.
[122]张洪杰，孟健，唐定骧.高性能镁-稀土结构材料的研制、开发与应用[J].中国稀土学报，2004,(22):40-46.
[123]陈振华.耐热镁合金[M].北京：化学工业出版社，2007.
[124]余强国，等.稀土镁合金的发展、应用及开发[J].稀有金属与硬质合金，2006，3:36-38.
[125] Rokhlin LL. Magnesium Alloys Containing Rare earth Metals [M]. London and NewYork: Taylor&Francis Group,2003.
[126] Iwasawa S, Negishi Y, Kamado S, Kojima Y, Ninomiy R, Age HardeningCharacteristics and High Temperature Tensile Properties of Mg-Gd and Mg-Dy alloys [J].Journal of Japan Institute of Light Metals,1994,44:3-8.
[127] Kamado S, Iwasawa S, Ohuchi K, Kojima Y, Ninomiy R, Age HardeningCharacteristics and High Temperature Tensile Properties of Mg-Gd and Mg-Dy Alloys [J].Journal of Japan Institute of Light Metals,1994,42:727-733.
[128]孟健，佟国栋，张洪杰等.稀土镁中间合金的研究与应用[C].第63届世界镁业大会暨国际镁协2006年年会论文集，2006：38-47.
[129] I.P. Moreno, T.K. Nandy, J.W. Jones, J.E. Allison, T.M. Pollock. Microstructuralstability and creep of rare-earth containing magnesium alloys [J]. Scripta Materialia,2003,48:1029-1034.
[130] Ben-Hamu, G; Eliezer, D; Shin, KS. The Relation between Microstructure andCorrosion Behavior of New Mg-Al-X Alloys for Transportation Application [J].CORROSION, PROCESSES AND ADVANCED MATERIALS IN INDUSTRY,2010,(95):43-46.
[131] Garboggini A, Mcshane HB. Effect of Zn and Si Additions on Structure andProperties of Rapidly Solidified Mg-Al alloys [J]. Materials Science and Technology,1994,9:763-769.
[132] Srinivasan, A; Pillai, UTS; Pai, BC. Effects of elemental additions (Si and Sb) on theageing behavior of AZ91magnesium alloy [J]. MATERIALS SCIENCE ANDENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTUREAND PROCESSING,2010,527(24-25):6543-6550.
[133] Polmear I J. Magnesium alloys and application [J]. Mater Sci Tech,1994,10:1-14.
[134] Padezhnova EM, Melnik EV, Miliyevskiy RA, Dobatkina TV, Kinzhibalo VV.Investigation of the Mg-Zn-Y System [J]. Russian Meatl (Engl Transl),1982,4:185.
[135] Zhang, P; Lindemann, J; Ding, WJ, et al. Effect of roller burnishing on fatigueproperties of the hot-rolled Mg-12Gd-3Y magnesium alloy [J]. MATERIALS CHEMISTRYAND PHYSICS,2010,124(1):835-840.
[136] Nair KS, Mittal MC, Rare Earths in Magnesium Alloys [J]. Materials Science Forum,1998,30:89-104.
[137] Petterson G, Westengen H, Hoier R, Lohne O. Microstructure of A Pressure Die CastMagnesium-4wt.%Aluminium Alloy Modified with Rare Earth Additions [J]. MaterialsScience and Engineering A,1996,207(1):115-120.
[138] Yi S, Park ES, Ok JB, Kim WT, Kim DH.(Icosahedral phase+Mg) Two PhaseMicrostructures in the Mg-Zn-Y Ternary System [J]. Materials Science and Engineering A,2001,300(1-2):312-315.
[139] Yoshida T, Itoh K, Tamura R, Takeuchi S. Plastic Deformation and Hardness inMg–Zn–(Y, Ho) Icosahedral Quasicrystals [J]. Materials Science and Engineering A,2000,294-296:786-789.
[140] Zhao DS, Tang YL, Luo ZP, Shen NF, Wang RH, Zhang SQ. The Face-centeredIcosahedral Quasicrystalline Phase in Mg-Zn-Y-Zr Alloys [J]. Materials Letters,1995,23(4-6):277-281.
[141] Luo ZP, Zhang SQ, Tang YL, Zhao DS. On the Stable Quasicrystals in SlowlyCooled Mg-Zn-Y Alloys [J]. Scripta Metallurgica and Materialia,1995,32:1411-1416.
[142] Tang YL, DS Zhao, Luo ZP, Shen NF, Zhang SQ. On The Chemical CompositionAnalysis of the Qcosahedral Phase in an Mg-Zn-Y-Zr Ingot [J]. Journal of Alloys andCompounds,1994,204(1-2):17-19.
[143] Yuan GY, Liu Y, Ding WJ, Lu C, Effects of Extrusion on The Microstructure andMechanical Properties of Mg-Zn-Gd Alloy Reinforced With Quasicrystalline Particles [J].Materials Science and Engineering A,2008,474:348-354.
[144] Kamado S, Ashie T, Ohshima Y. Tensile Properties Andformability of Mg-Ligrain-refined ECAP process [J]. Mater Sci Forum,2000,350-351:55-62.
[145] Decker R F.The Renaissance in Magnesium [J].Advanced Materials&Processes，2004，154(3)：31-33.
[146] I. P. Moreno, T. K. Nandy, J. W. Jones, J. E. Allison, T. M. Pollock. Microstructuralcharacterization of a die-cast magnesium-rare earth alloy [J]. Scripta Materialia,2001,(45):1423-1439.
[147] L. Y. Wei, G. L. Dunlop, H. Westengen. Precipitation hardening of Mg-Zn andMg-Zn-RE alloys [J]. Metall. Mater. Trans. A,1995,(26):1705-1706.
[148] Qi-chi LE, Zhi-qiang ZHANG, Zhi-wen SHAO, Jian-zhong CUI, Yi XIE.Microstructures and mechanical properties of Mg-2%Zn-0.4%RE alloys [J]. Transactions ofNonferrous Metals Society of China,2010,20:352-356.
[149] H. Yao, Y. Li, A. T. S. Wee. Passivity behavior of melt-spun Mg-Y alloys.Electrochimica Acta,2003,(48):4197-4204.
[150] O. Fruhwirth, G. W. Herzog, I. Hollerer, A. Rachetti. Dissolution and hydrationkinetics of MgO [J]. Surf. Technol.,1985,(24):301-317.
[151] MORDIKE BL, EBERT T. Magnesium: properties-applications-potential [J].Materials Science and Engineering A,2001,302(11):37-45.
[152] ANTION C, DONNADIEU P, PERRARD F, DESCHAMPS A, TASSIN C. PISCH A.Hardening precipitation in a Mg-5Y-3RE alloy [J]. Acta Materialia,2003,51:5335-5348.
[153] APPS PJ, KARIMZADEH H, KING JF, LORIMER GW. Precipitation reactions inMagnesium-rare earth alloys containing Yttrium, Gadolinium or Dysprosium [J]. ScriptaMaterialia,2003,48:1023-1028.
[154] P. Mengucci. Structure evolution of a WE43Mg alloy submitted to different thermaltreatments [J]. Materials Science and Engineering A,2008,479:37-44.
[155] PING DH, HONO K, NIE JF. Atom probe characterization of plate-like precipitatesin a Mg-RE-Zn-Zr casting alloy [J]. Scripta Materialia,2003,48:1017-1022.
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