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

Abstract

The pre-precipitation processes of ordered intermetallic compound L12 (Ni3Al) in binary Ni–14.0at.%Al alloy, L12 (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 L12 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 L10 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 L10 (M=1) phase; if the L12 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 L10 phase.