Ce与Cr协同作用B2-NiAl合金力学性能的理论研究  

First-Principles Study on Mechanical Properties of B-NiAl Intermetallic Compound Alloyed by Ce Cooperation with Cr

作　　者：陈律[1] 刘逸众 李敏 Chen Lu;Liu Yizhong;Li Min(Changsha Aeronautical Vocational and Technical College,Changsha 410124,China)

机构地区：[1]长沙航空职业技术学院,湖南长沙410124

出　　处：《稀有金属材料与工程》2020年第9期3065-3070,共6页Rare Metal Materials and Engineering

基　　金：湖南省自然科学基金科教联合基金(2017JJ5057)。

摘　　要：采用第一性原理赝势平面波方法,基于虚拟晶体势函数近似(VCA),研究了不同浓度x(x=0 at%-2.2 at%)的Ce和Cr单独及协同合金化对B2-NiAl晶体弹性模量E、剪切模量G、Cauchy压力参数及G/B0比值的影响。结果表明:Cr占据Ni原子位能显著提高B2-NiAl合金的剪切模量G和弹性模量E,而Ce占据Al原子位则能降低其合金的G和E随着合金化浓度提高到2.1 at%,Cr占据Al原子位能改善B2-NiAl合金的延性,而当Ce取代Al原子位协同Cr取代Al原子位时,对其延性的改善效果比各自单独合金化的效果更显著,且以合金化浓度为2.0 at%时为最佳效果。这一理论计算很好的重现了实验中Ce与Cr协同合金化明显提升B2-NiAl合金室温延性的现象。电子态密度分析显示,Cr原子或者Cr协同Ce原子能够削弱B2-NiAl晶体当中的Ni(d)-Ni(d)主要成键峰的杂化效应,降低主要成键峰的方向性。The effect of alloying concentration x(x=0~2.2 at%)on Cauchy pressure,elastic modulus E,the shear modulus G and their ratio G/B0 of B2-NiAl supercells alloyed by Cr and Ce,alone or together,was calculated in the framework of Virtual Crystal Approximation(VCA)by the first-principles pseudopotential plane-wave method.Results show that the shear modulus G and elastic modulus E of B2-NiAl alloy are significantly increased when Cr occupies the Ni atom site in B2-NiAl crystals,while the G and E will be reduced when Ce occupies the Al atom site.With the alloying concentration increasing to 2.1 at%,the ductility of B2-NiAl crystals can be improved with Cr occupying the Al atom site.It is worth emphasizing that the ductility of B2-NiAl crystals is improved more significantly when Ce and Cr replace A1 atom site simultaneously than that alloyed by Ce or Cr alone,especially when the alloying concentration x is 2.0 at%.The calculation result herein explains the phenomenon that the room temperature ductility of B2-NiAl alloy is enhanced obviously by Cr cooperation with Ce.The electronic density of states shows that Cr atoms or Cr cooperation with Ce atoms all can weaken the hybridization effect of the main bonding peaks of Ni(d)-Ni(d)and decrease the directivity of the main bonding peaks in B2-NiAl crystal.

关 键 词：B2-NiAl Ce和Cr合金化 VCA近似 力学性质 

分 类 号：TG146.2[一般工业技术—材料科学与工程]