Nb合金化对Ti_5Si_3韧性影响的理论研究

利用基于密度泛函理论的第一性原理,通过计算弹性常数、体模量B以及剪切模量G以及经验常数G/B、泊松比和柯西压力预测(Ti1-xNbx)5Si3的韧脆性;并利用态密度以及差分电荷密度从电子角度给予解释。结果表明:随Nb含量的增加,其韧性逐渐增强。从电子结构角度分析(Ti1-xNbx)5Si3韧性增加的原因:Nb的加入使得Ti6g3d电子与Si3p电子强键结合减弱;沿c轴方向原子键合强烈的方向性发生改变;同时(001)面间距增大。

Theoretical research on the toughness properties of Nb alloyed Ti5Si3

The shear modulus, bulk modulus and empirical constants of G/B ratio, Poisson, ratio, Cauchy pressure of Ti5Si3 were calculated using first-principles methods which was based on density functional theoryto predict the toughness of （Til-xNbx） 5Si3, the results was explained by denisity of states and charge denisity difference. The calculated results showed that toughness increased with niobium addition. The increased toughness was attributed to the bonding between the Ti6g3d and Si3p electrons weaken; the bonding direction along the c axis modified and the distance of （ool） was lager after niobium addition.