Computational study of the DO 3+ L 2 1 two-phase field in β Cu–Al–Mn

Abstract

The two-phase miscibility gap occurring at moderate and low temperatures in the ternary Cu--Al--Mn alloy is studied by numerical techniques. The limits of the coexistence region between a DO 3 —paramagnetic phase with composition close to equiatomic Cu 3Al , and a L 2 1 —ferromagnetic phase with composition near the Heusler Cu 2AlMn alloy are studied by means of Monte Carlo simulations. A model Hamiltonian including both chemical and magnetic interactions is employed; simultaneous evolution of the atomic and magnetic configurations is allowed. The influence of the magnetic interactions on the formation of the two-phase miscibility gap is analysed. It is found that the magnetic interactions between the Mn atoms can account, in part, for the phase separation, although this is hardly explainable in these terms only.