Effect of pressure on the phase stability, elastic anisotropy, and physical properties of CuZr structures

Abstract

The effect of hydrostatic pressure on the relative stabilities of the four main structures in CuZr has been estimated using first-principles calculations. The results indicate that hydrostatic pressure induces the B19′ → B19 transformation at ~40 GPa and Cm → B19 transformation at ~68 GPa. At 0 GPa, these CuZr structures exhibit analogous values of B, G, and E and small difference in σ. However, the differences between these structures become appreciable in B, G, E, and σ values. 3D graphs of Young's modulus reflect the elasticity is directional. Pressure promotes the increase of elastic anisotropy degree of B2. For B19′ and Cm, the variation trends under pressure firstly decrease, then slightly increase, while that is opposite for B19. The quasi-harmonic Debye model is used to evaluate the effects of temperature and pressure on the thermodynamic properties (heat capacity, thermal expansion coefficient, Debye temperature, and Grüneisen parameter) of the CuZr structures.