Effects of Ni and Ti on the phase stability, martensitic transformation and mechanical properties of B2 CuZr phase

We systematically investigate the phase stability, martensitic transformation (MT) behavior and mechanical properties of Ni or Ti doped B2 CuZr phase with the supercell and virtual crystal approximation (VCA) methods. Formation energies of different supercells are used to judge the preference site of the dopants and to study the alloying effects on the stability of CuZr phase. By analyzing the alloying effects on two cubic elastic moduli (C' and C-44), we make a prediction of the composition-dependent martensitic transformation start temperature (Ms), which may give a theoretical interpretation of the different experimental observations for the Ni doped CuZr alloys and may also explain the effects of Ti on the decreasement of Ms from Ti's destabilizing-effect induced decomposition of CuZr alloys. In addition, with the calculated elastic constants, mechanical properties including ductility and negative Poisson's ratio (PR) of the Ni or Ti doped CuZr alloys are also discussed. (C) 2015 Elsevier B.V. All rights reserved.