Characterization of lattice defects for L12–Ni3Al involving the ordering process via the microscopic phase field method

The quantitative and temporal-evolutional advantages of the microscopic phase field are used to study the lattice defects of the L12–Ni3Al(γ′) phase in a ternary Ni–Al–V system. The temporal evolutional process of the occupancy of each individual atom conforms to classical nucleation processes, where the occupancy is constant at the incubation period, and then fluctuates up or down during segregation and equilibrium at the coarsening period. The α sublattice of the L12 structure is almost completely occupied by regular NiNi with a small amount of antisite defect AlNi and the substitutional defect VNi at the equilibrium state. By sharp contrast, the β sublattice is predominantly occupied by regular AlAl, as well as the non-negligible antisite defect NiAl and substitutional defect VAl. Regular atoms have a negative correlation with temperature; hence, the defects are positive. By comparison, the β sublattice, which accommodates most of the defects in Ni3Al, is more sensitive to temperature than the α sublattice. The results are generally in line with comparisons reported by other scientists.

► The quantitative relation between ordering stages and lattice defect was presented.
► Temperature–lattice defect relationship was studied giving a positive trend.
► Substitution law is clarified with a good explanation.
► The LRO of γ′ holds but phase transition from θ to γ′ is facilitated by substitution.