Anisotropic Phase Transformation in B2 Crystalline CuZr Alloy.

B2 phase copper-zirconium (CuZr) particles are often used as an enhancement agent to improve the toughness of metallic glass; however, the orientation dependence of its phase transformation behaviors under loading remains unclear. In this work, molecular dynamics simulation of uniaxial tension and compression of B2 phase CuZr along different crystallographic orientation are performed to investigate the orientation-related mechanical response and phase transformation mechanisms. It was found that the mechanical behavior of CuZr exhibits obvious tension/compression asymmetry, but their failure mode is mainly local amorphization. Three different phase transformation behaviors, B2→FCC, B2→BCT, and B2→HCP, were observed in tension and compression along [001], and tension along [110], respectively. The transformations are realized by lattice rotation (~ 5°), uniform deformation and separation between Cu and Zr atomic layers, respectively. Before failure by local amorphization, phase transformation region can be recovered after unloading, showing the superelasticity.