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

Aiming to improve γ′ 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 γ/γ′ dual-phase was carried out through a complete microstructural analysis and micro and nano hardness measurements. The composition of the γ (fcc)-matrix and γ′ (L12)-precipitates, the nanoscale properties including γ′ volume fraction and γ/γ′ 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 γ' volume fraction and thermal stability for long ageing time detecting slow coarsening.