Dissolution behaviour of the γ′ precipitates in two kinds of Ni-based superalloys

Abstract

The effects of high heating temperature and short dwell time on the evolution of γ′ precipitates were investigated in two kinds of Ni-based superalloys. The microstructural evolutions of the samples were characterised by qualitative and quantitative metallography during various heating cycles, and the dissolution kinetics were then evaluated. The results illustrated that the heating temperature plays a more predominant role in the dissolution of γ′ precipitates than the dwell time. Meanwhile, the γ′ morphology in the dissolution process was strongly influenced by the elastic strain energy associated with the lattice mismatch between γ and γ′ phases. For IN 100 alloy, the γ′ evolution was dominated by the elastic interaction energy between adjacent precipitates, but for DS Rene 125 alloy, the γ′ precipitates kept a regular arrangement along the [001] softest directions in the dissolution process. On increasing the dwell time for the two kinds of superalloys, the dissolution rate of γ′ gradually decreased, and the dissolution activation energy gradually increased. However, the dissolution activation energy for IN 100 alloy was different from that of DS Rene 125 alloy under the same heating conditions.