Microscopic Phase-Field Simulation of Atom Substitution Behaviour in Ni--Cr--Al Alloy

Simulations are performed on atom substitution behaviour in Ni₇₅Al_25-xCr_x alloys based on a microscopic phase-field model at 873K. The ordering of both the Al and Cr atoms takes place simultaneously, Cr occupies both the Al and Ni sites with a preference for the Al sites, and Cr and Al atoms together occupy the β -sites, and the complex γ’ Ni₃(Al_1-xCr_x) (L1₂ structure) phases are formed during the precipitation. At the ordering boundary of L1₂ phases, Cr atoms occupy the Al sites, then Ni₃Cr phases are formed.