Nonstoichiometry and Defect Mechanism in Intermetallics with L1₂-Structure

Abstract

A statistical-thermodynamic model was derived which allows to describe thermodynamic activities in intermetallic compounds with L1 2 -structure as a function of composition and temperature. The energies of formation of the four types of point defects (anti-structure atoms and vacancies on both sublattices) were used as adjustable parameters. The model was applied to the three compounds Ni 3 Al, Ni 3 Ga, and Pt 3 Ga, and it permitted to estimate for the first time the defect formation energies for Ni 3 Ga and to provide initial estimates for Pt 3 Ga.