Impact of ageing processes on occupancy probability of L1₂ and D0₂₂ phase: Studied by microelasticity phase field model

The microelasticity phase field model was used to study the occupancy probability (OP) of L1₂-Ni₃Al and D0₂₂-Ni₃V phase which suffered the 1000 K and 1200 K single temperature ageing process (1000 K STAP, 1200 K STAP), 1000 K and 1200 K cyclic temperature ageing process (CTAP), respectively. During the transformation of ageing processes from 1000 K STAP via CTAP to 1200 K STAP the OP of regular atoms Ni_Ni and Al_Al in L1₂ phase together with Ni_Ni and V_v in D0₂₂ phase decrease with time, but the antisite defect Ni_Al, Ni_V, V_Ni, and Al_Ni together with the substitutional defects Al_Ni, Al_V, and V_Ni increase with time. The OP of Ni_Ni in L1₂ is higher than Ni_Ni in D0₂₂, but Al_Al is lower than V_V, additionally, the OPs of defect in L1₂ are generally greater than that of D0₂₂. The temporal evolution curves of CTAP are "great wall" like and the peek values are lower than the relevant higher values of the other two but trough values higher than the relevant lower ones.