Phase-field study on the pre-precipitated phase of ordered intermetallic compounds in binary and ternary Ni-Al base alloys

The pre-precipitation processes of ordered intermetallic compound L1(2) (Ni3Al) in binary Ni-14.0 at.% Al alloy, L1(2) (Ni3Al) and DO22 (Ni3V) in ternary Ni-Al-V alloy were studied using the microscopic phase-filed dynamic model. It is found that prior to the formation of L1(2) or DO22 ordered phase, a pre-precipitated phase appears first. For the binary alloy, Ni atoms aggregate on (002) plane and deplete on (001) plane, Al atoms aggregate on (001) plane and deplete in (002) plane, the pre-precipitated phase is L1(0) phase. For the ternary alloy, if the DO22 ordered phase appears first, Ni atoms aggregate on (002) plane and deplete on (001) plane, the aggregation and ordering of V atoms on (001) plane are faster than those of Al atoms, the pre-precipitated phase is L1(0) (M = 1) phase; if the L1(2) ordered phase appears first, Ni atoms aggregate on (002) plane and deplete on (001) plane, the aggregation and ordering of Al atoms on (001) plane are faster than those of V atoms, the pre-precipitated phase is L1(0) phase. (C) 2015 Elsevier B.V. All rights reserved.