Influence of aging time on microstructural evolution and mechanical properties of FGH2907 alloys

The near-net-shape forming of alloy rings is regarded as the promising approach for manufacturing critical components in aero-engines. The FGH2907 alloy powders were prepared by plasma rotating electrode process, and the FGH2907 alloys were fabricated by hot isostatic pressing. The specimens were subjected to solution and aging heat treatments for 1 h, 2 h, and 4 h, respectively. The effects of aging time on microstructural evolution and mechanical properties of the FGH2907 alloys were investigated. Results show that, with the prolonged aging time, the tensile strength initially increases and then decreases, while the ductility first decreases and then slightly recovers. After 1 h of aging, the γ′ phases are uniformly and finely dispersed within the matrix, and the ε phase content is low, resulting in the optimal balance between strength and ductility. After 2 h of aging, the needle-like ε phases and the spherical γ′ phases coarsen significantly, leading to the marked increase in strength but the sharp decline in ductility. After 4 h of aging, the secondary nucleation of the ε phases and γ′ phases occurs, weakening the precipitation hardening, leading to the reduce in strength and the slight recovery in ductility.