Microstructure stability and hardening determination through heat treatment of sintered Co γ/γ′ based alloys

Aiming to improve gamma ' volume fraction through alloying elements and heat treatments, the influence of the combined effect of 2 Ti and 2 Ta addition (at%) to a nominal Co-12Al-10W at.% Co-based superalloy, and the heat treatments parameters have been investigated. The Co-based alloys were manufactured by PM using mechanical alloying for powder processing, and a field-assisted sintering technique to consolidate the material. The specific study of solution temperatures and ageing times to promote the gamma/gamma ' dual-phase was carried out through a complete microstructural analysis and micro and nano hardness measurements. The composition of the gamma (fcc)-matrix and gamma ' (L12)-precipitates, the nanoscale properties including gamma ' volume fraction and gamma/gamma ' misfit were measured as a function of increasing solution and ageing time. In the end, Ti and Ta addition to the Co-12A-10W alloy increases gamma' volume fraction and thermal stability for long ageing time detecting slow coarsening.