摘要
采用第一原理方法,计算了MoSi2及其三元合金(Mo,M)Si2(M=Nb、Tc、Ta、W)的电子结构,表面能(γs),不稳定层错能(γus),以及弹性常数。从"韧化参数"D=γs/γus以及弹性性质两个方面研究了合金化对MoSi2韧性的影响。研究表明,MoSi2(001)Si-|-Si具有较低的表面能,是最可能的解理面;带有方向性的强Mo4d-Si3p共价键是MoSi2本征脆性的最主要原因。Nb、Tc、Ta合金化有利于增强MoSi2的韧性;W则起到增脆作用。合金增韧的主要原因是弱M4d-Si3p键代替了方向性的强Mo4d-Si3p键。
With first-principles method,electronic structure,surface energy（γs）,unstable stacking fault energy（γ us）,and the elastic parameters of MoSi2 and（Mo,M）Si2（M= Nb,Tc,Ta,W）were obtained.By combining a ＂disembrittlement parameter＂ D=γs/γ us and elastic properties,the influence of alloying elements on ductility was investigated.Ideal MoSi2 crystal investigation shows that MoSi2（001）Si-｜-Si plane with lower surface energy is preferred cleavage plane.Intrinsic brittlement of MoSi2 is caused by strong directional covalent Mo4d-Si3p bonding.Nb,Tc,and Ta alloying are found to be beneficial to the enhancement of ductility.In contrast,W alloying embrittles MoSi2.Softening effect can be interpreted by the replacement of Mo4d-Si3p bonding by weaker and less directional M4d-Si3p bonding.
出处
《材料科学与工程学报》
CAS
CSCD
北大核心
2010年第2期232-236,共5页
Journal of Materials Science and Engineering
