The Electronic Origin of the Underestimated Trigonal Shear Constant of Zr1-x,Nb-x Super Alloys from First-Principles Calculations
- 材料学院－已发表论文 
Zr1-x_Nb-x binary alloys are important biomaterials having high strength-to-weight ratio, plasticity, and biocompatibility. In this study, the trigonal shear constant (C-44) of Zr1-x,Nbx was found to be underestimated from the first-principles calculations. The origin of the undervalued C-44 was unraveled using the ordered supercell and the disordered special quasirandom structure methods (x= 0.25, 0.5, and 0.75). The analysis of the electronic structure revealed that the underestimation of the C-44 of Zr1-x,Nb-x is mainly caused by the underestimated C-44 of Nb and that C-44 could be increased by adopting the special quasirandom structure method. Compared to the supercell method, the special quasirandom structure method predicted not only an increase in the C-44 of Zr1-x,Nb-x with decreases in x from 0.75 to 0.5, but also a negative deviation for x= 0.25 in the trend of C44, which resulted from the softening in the body-centered cubic structure. Moreover, we found that the Young's modulus of special quasirandom structure Zr0.75Nb0.25 was in excellent agreement with that of human bones in the  direction. This work is of significance to the field of "super alloys" and artificial bones.