Time Evolution of Long‐Range Ordering in Fe–Pt Alloys

Abstract

A method to calculate the atomic long‐range order (LRO) parameter and the time to reach an asymptotic LRO value is proposed and applied to a wide concentration range of Fe–Pt alloys with fcc crystal structure. The equation for the time evolution of the LRO parameter is based on a phenomenological approach with Onsager kinetic coefficients as diffusion coefficients for an alloy that undergoes complex combination of phase transformations, that is, atomic and magnetic ordering and martensitic transformation. The microscopic phase‐field kinetic model that was first proposed by Khachaturyan is applied. The energy parameter mixing energy that defines the kinetics of the LRO is considered as a sum of “paramagnetic” (electrochemical + strain‐induced interactions) and Ising‐type magnetic contributions.