On the antiphase boundary energy of Ni 3(Al, Ti) particles

Abstract

The purpose of the work reported in this paper was to investigate the relationship between the antiphase boundary (APB) energy of the γ′ (Ni 3(Al, Ti)) particles grown in an FeNiCr alloy and their chemical composition. The experimental measurements were carried out on four laboratory heats of Alloy 800 which differed from each other only in slight variations in the titanium and aluminium contents. The APB energies were derived from a characterization of both the mechanical properties and the microstructure of specimens submitted to thermal aging for different times. The chemical composition of the γ′ particles was obtained by X-ray microanalysis on extraction replicas prepared on the aged materials. A relationship was determined on the assumption that only the atomic configurations adjacent to the slip plane, both before and after the gliding of the dislocation, control the APB energy. The resulting expression was fitted to the experimental data obtained here as well as to the value of the APB energy of the binary γ′ (Ni 3Al) given in the literature, in order to obtain the value of the parameters appearing in the expression. The resulting relationship can explain both the generally observed increase in the APB energy with increasing titanium content of the alloy and the low value of the same parameter measured in Nimonic PE16 alloy.