Fe对NiAl力学性能影响的第一原理计算

采用第一原理赝势平面波方法,基于虚拟晶体势函数近似(VCA),计算Fe合金化(浓度x<3.0%,原子分数,下同)时完整与缺陷B2-NiAl晶体的弹性性质,并采用弹性常数C44、Cauchy压力参数(C12-C44)、杨氏模量E、剪切模量G及其与体模量B0的比值G/B0等,表征和评判Fe合金化浓度x对NiAl金属间化合物延性与硬度的影响。结果表明:无论是无缺陷的理想NiAl晶体,还是含Ni空位或Ni反位的NiAl缺陷晶体,x<0.6%的Fe合金化均可使其硬度大幅提高。Fe合金化浓度低于0.5%时,虽然完整NiAl晶体的延性变差,但含Ni空位的缺陷NiAl晶体的延性却可明显改善,并以x=0.2%～0.4%时韧化效果最好。Ni空位或Ni反位降低B2-NiAl晶体的本征延性。实验中0.20%～0.25%的Fe合金化对NiAl晶体延性的改善很可能源于Fe原子与NiAl晶体中Ni空位间的关联与协同作用。

First-Principles Calculation on Mechanical Properties of B2-NiAl Intermetallic Compound with Fe Addition

Using the first-principles pseudopotential plane-wave methods based on the density functional theory,the elastic constants of B2-(Ni1-xFex)Al(x=0-3.0 at%) supercells with or without Ni vacancy or Ni anti-site defect were calculated in the framework of Virtual Crystal Approximation.Several parameters,such as elastic constant C44,Cauchy pressure(C12-C44),Young modulus E,the shear modulus G and their ratio G/B0,have been adopted to characterize and assess the effect of Fe alloying concentration on the ductilit...