Phase Equilibria in Co-rich Co-Al-W alloys at 1300°C and 900°C

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