Regulating the coarsening of the γ' phase in superalloys

Abstract

The properties of superalloys are typically deteriorated by the coarsening of the nano-sized γ' phase, which is the primary strengthening component at high temperatures. Stabilizing the γ' phase represents one of the key challenges in developing next-generation superalloys. Herein, we fabricate a cobalt-nickel-based superalloy with a nanoscale coherent γ' phase, (Ni,Co)3 (Al,Ti,Nb), which is isolated by stacking-fault ribbons in the alloy matrix as a result of the Suzuki segregation of alloying atoms. Additionally, we demonstrate that this new nanostructure can slow down the coarsening of the γ' phase at high temperatures. As a result, the cobalt-nickel-based superalloy displays considerably high tensile yield points, exceeding 1650 MPa at room temperature and 1250 MPa at 973 K, which are markedly higher than those of the commonly used nickel- and cobalt-based superalloys. This study thereby paves a new path for developing superalloys with exceptional mechanical performance and thermal stability.