Phase Equilibria in Co-Rich Co-Al-W Alloys at 1300°C and 900°C

Abstract

The phase equilibria of Co-base trial alloys of Co-9Al-7.5W, Co-5.5Al-10W and Co-9Al-3W at 1300°C and 900°C were determined in the present investigation. The experimental alloys were γ single-phase alloys at 1300°C, although the existence of the γ' phase and the ε phase was identified due to cooling effect. The nearly cuboidal γ' phase and the plate-like DO19 phase in alloys 9Al-7.5W and 5.5Al-10W were coarsened after long-term annealing at 900°C. It is suggested that the alloy 9Al-7.5W was in γ+γ' two-phase region, while the alloys 5.5Al-10W and 9Al-3W were in γ+DO19 two-phase region and γ singe-phase region at 900°C, respectively.