Effect of Nb on the Properties of Ti-Nb Random Alloys from First-principles
作者单位：State Key Laboratory of Solidification Processing Northwestern Polytechnical University
会议名称：《中国材料大会2012》
会议日期：2012年
学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）]
基 金：financially supported by the National Basic Research Program (973) of China (No. 2012CB619101) the Project of Introducing Talents of Discipline to Universities (No. B08040)
关 键 词：Ti-Nb First principles Phase stability Mechanical properties.
摘 要：The effect of Nb on the equilibrium lattice parameters and relative stability between β and ω phases of Ti1-xNbx （0 x ≤ 0.4） random alloys as well as their mechanical properties in body-centered-cubic crystallographic phase was investigated using the exact muffin-tin orbitals method in combination with the coherent potential approximation. It has been found that the calculated lattice parameters of the β phase agree well with the experimental data. For ω phase, the value of a increases almost linearly with increasing Nb concentration, while the opposite situation presented for c/a. Both Nb addition and increasing temperature enhanced the stability of β phase relative to ω phase. The critical Nb concentration for the complete stabilization of β phase at 300 K, 673 K and 1273 K was 22 at.%, 17 at.% and 9 at.%, respectively. The polycrystalline bulk modulus B, Young’s modulus E and shear modulus G increased monotonously with Nb addition and reducing the Nb concentration below 30 at.% resulted in lower E compared to that of Ti-6Al-4V. The calculated G/B values demonstrate that the bcc Ti1-xNbx （0 x ≤ 0.4） random alloys should be intrinsically ductile.