Energy studies of precipitation sequence in Ni75Al10Cr15 alloy based on the phase field theory

Abstract

Based on the phase field theory, the phase precipitation sequence of Ni75Al10Cr15 alloy and the free energy of each phase were studied. Moreover, the interatomic potentials of L10 phase, L12 phase and DO22 phase changing with temperature and concentrations were computed through utilizing the interatomic potentials equations induced by Khachaturyan’s relational equations between the interatomic potentials and the long-range order (LRO) parameters. Results match preceding work and demonstrate that the phase precipitation sequence of Ni75Al10Cr15 alloy is the disordered phase → L10 pre-precipitation phase → L12 equilibrium phase → L12+DO22 equilibrium phase. Free energies of L10 pre-precipitation phase are higher and interatomic potentials are smaller than those of L12 equilibrium phase; therefore, it is concluded that L10 phase is unstable, and phase transformation would occur to L12 which is more stable; L12 phase precipitates earlier than DO22 phase because L12’s interaction potentials are larger than DO22’s.