反应堆压力容器钢中溶质元素空位型扩散机理研究
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摘要
辐照或热老化导致元素偏析和沉淀析出是反应堆压力容器(reactor pressure vessel,RPV)钢性能退化的主要影响因素,点缺陷与合金/杂质元素结合与扩散是引起元素偏析和沉淀析出的主要原因。本文利用分子动力学方法研究了反应堆压力容器钢中几种主要合金/杂质元素(Cu、Ni、Mn、P)的空位型扩散机理。研究了空位与合金/杂质元素的结合性能;基于多频模型计算了合金/杂质元素的空位风参数和扩散系数。通过计算发现,Cu、P与第1近邻、第2近邻空位均具有较大的结合能,Ni与第2近邻空位具有较大的结合能;溶质元素的空位风均随着温度的升高而增大,表明在高温下合金/杂质元素均倾向通过与空位互换位置而扩散。
The diffusion of solutes in reactor pressure vessel(RPV)steel,accompanied with point defects,will result in the formation of precipitation and segregation on grain boundary,which will cause the hardening and embrittlement of materials.In order to deeply understand the performance degradation of RPV steel,the knowledge on solute diffusion mechanism is required.The vacancy-mediated diffusion mechanism of major solutes in RPV steel was studied by molecular dynamics method.Firstly,solute-vacancy interactions were studied.Subsequently,based on multi-frequency model,the vacancy drag factor and diffusion coefficient were calculated.The results show that Cu and P have strong binding energies with vacancies both in the first nearest neighbor(1nn)and the second nearest neighbor(2nn),and Ni has stronger binding energy with 2nn vacancy than 1nn vacancy.The vacancy drag factor increases with temperature,which means that solutes diffuse by exchanging with vacancy at high temperature.
The diffusion of solutes in reactor pressure vessel(RPV)steel,accompanied with point defects,will result in the formation of precipitation and segregation on grain boundary,which will cause the hardening and embrittlement of materials.In order to deeply understand the performance degradation of RPV steel,the knowledge on solute diffusion mechanism is required.The vacancy-mediated diffusion mechanism of major solutes in RPV steel was studied by molecular dynamics method.Firstly,solute-vacancy interactions were studied.Subsequently,based on multi-frequency model,the vacancy drag factor and diffusion coefficient were calculated.The results show that Cu and P have strong binding energies with vacancies both in the first nearest neighbor(1nn)and the second nearest neighbor(2nn),and Ni has stronger binding energy with 2nn vacancy than 1nn vacancy.The vacancy drag factor increases with temperature,which means that solutes diffuse by exchanging with vacancy at high temperature.
引文
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[19]DRUCE S G,GAGE G,JORDAN G.Effect of ageing on properties of pressure vessel steels[J].Acta Metall,1986,34:641-652.
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[21]LeCLAIRE A D.Impurity diffusion in iron group metals[M].Berlin:Springer,1990:124-130.
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[25]BORG R J.The diffusion of gold,nickel and cobalt in alpha iron:A study of the effect of ferromagnetism upon diffusion[J].Acta Metall,1963,11:861-866.
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[27]BARASHEV A V,AROKIAM A C.Monte Carlo modelling of Cu atom diffusion inα-Fe via the vacancy mechanism[J].Phil Mag Lett,2006,86:321-332.
[28]CHOUDHURY S,BAENAED L,TUCKER J D,et al.Ab-initio based modeling of diffusion in dilute BCC Fe-Ni and Fe-Cr alloys and implications for radiation induced segregation[J].J Nucl Mater,2011,41:11-14.
[2]Integrity of reactor pressure vessels in nuclear power plants:Assessment of irradiation embrittlement effects in reactor pressure vessel steels[R].Vienna:IAEA,2009.
[3]LeCLAIRE A D.Solute diffusion in dilute alloys[J].J Nucl Mater,1978,69&70:70-96.
[4]ACKLAND G J,MENDELEV M I,SROLOVITZ D J,et al.Development of an inter atomic potential for phosphorus impurities inα-iron[J].J Phys:Condens Matter,2004,16:1-14.
[5]PASIANOT R C,MALERBA L.Interatomic potentials consistent with thermodynamics:The Fe-Cu system[J].J Nucl Mater,2007,360:118-127.
[6]BONNY G,PASIANOT R C.Fe-Ni many-body potential for metallurgical applications[J].Model Simul Mater Sci Eng,2009,17:025010.
[7]BONNY G,TERENTY D,BAKAEV A,et al.On the thermal stability of late blooming phases in reactor pressure vessel steels:An atomistic study[J].J Nucl Mater,2013,442(1-3):282-291.
[8]OLSSON P,KLAVER T P C,DOMAIN C.Ab initio study of solute transition-metal interactions with point defects in bcc Fe[J].Phys Rev B,2010,81(5):054102.
[9]VOSKO S H,WILK L,NUSAIR M.Accurate spin-dependent electron liquid correlation energies for local spin density calculations:A critical analysis[J].Can J Phys,1980,58:1 200-1 211.
[10]GORBATOV O I,KORZHAVYI P A,RUBAN A V,et al.Vacancy solute interactions in ferromagnetic and paramagnetic bcc iron:Ab initio calculations[J].J Nucl Mater,2011,419:248-255.
[11]VINCENT E,BECQART C S,DOAMIN C.Ab initio calculations of vacancy interactions with solute atoms in bcc Fe[J].Nucl Instrum Methods Phys Res B,2005,228:137-141.
[12]BECQART C S,DOAMIN C.Ab initio contribution to the study of complexes formed during dilute FeCu alloys radiation[J].Nucl Instrum Methods Phys Res B,2003,202:44-50.
[13]MESSINA L,CHANG Z,OLSSON P.Ab initio modelling of vacancy-solute dragging in dilute irradiated iron-based alloys[J].Nucl Instrum Methods Phys Res B,2013,303:28-32.
[14]MILLER M K,PAREIGE P.Atomic level characterization of neutron irradiated pressure vessel steels[C]∥Mater Res Soc Symp Proc.[S.l.]:[s.n.],2001.
[15]NAGAI Y,TAKADATE K,TANG Z,et al.Positron annihilation study of vacancy-solute complex evolution in Fe-based alloys[J].Phys Rev B,2003,67:224202.
[16]MESSINA L,OLSSON P.Modelling of vacancy mediated diffusion in BCC iron based dilute alloys[C]∥4th n-FAME&22nd Fe-Cr Workshop.Edinburg:[s.n.],2013.
[17]GOLUBOV S I,SERRA A,OSETSKY Y N,et al.On the validity of the cluster model to describe the evolution of Cu precipitates in Fe-Cu alloys[J].J Nucl Mater,2000,277:113.
[18]LeCLAIRE A D,NEUMANN G.Numerical data and functional relationship in science and technology[M].Berlin:Springer,1990:130-179.
[19]DRUCE S G,GAGE G,JORDAN G.Effect of ageing on properties of pressure vessel steels[J].Acta Metall,1986,34:641-652.
[20]VATTER I A,HIPPSLEY C A,DRUCE S G.Review of thermal ageing data and its application to operating reactor pressure vessels[J].Int J Pres Ves Piping,1993,54:31-48.
[21]LeCLAIRE A D.Impurity diffusion in iron group metals[M].Berlin:Springer,1990:124-130.
[22]ANAND M S,AGARWAL R P.Diffusion of copper in iron[J].J Appl Phys,1966,37:42-48.
[23]GALE W F,TOTEMEIER T C.Metals reference book[M].San Francisco:Elsevier,2004.
[24]HIRANO K,COHEN M,AVERBACH B L.Diffusion of nickel into iron[J].Acta Metall,1961,9:440.
[25]BORG R J.The diffusion of gold,nickel and cobalt in alpha iron:A study of the effect of ferromagnetism upon diffusion[J].Acta Metall,1963,11:861-866.
[26]BOCQUET J,BREBEC G.Diffusion in metals and alloys[M].Amsterdam,Netherlands:Elsevier,1996.
[27]BARASHEV A V,AROKIAM A C.Monte Carlo modelling of Cu atom diffusion inα-Fe via the vacancy mechanism[J].Phil Mag Lett,2006,86:321-332.
[28]CHOUDHURY S,BAENAED L,TUCKER J D,et al.Ab-initio based modeling of diffusion in dilute BCC Fe-Ni and Fe-Cr alloys and implications for radiation induced segregation[J].J Nucl Mater,2011,41:11-14.