The plastic deformation ability of σ phase during creep in superalloys

Abstract

In superalloys, topologically close-packed (TCP) phases are strongly linked to the mechanical performance, but the evolution of their microstructures during creep remains elusive, hindering comprehensively understanding their impact on superalloys. In this work, we discover that the σ phase, one of the TCP phases, exhibits cooperative plastic deformation facilitated by stacking faults (SFs) in the (001)_σ plane. By utilizing multi-slice electron ptychography, the detailed structure and formation mechanism of these SFs are revealed. Creep experiments combined with micro-scale statistical analyses demonstrate that the σ phase can undergo cooperative plastic deformation during creep. Furthermore, macro-scale panoramic atlases prove the cooperative deformation of the σ phase has macroscopic representativeness. Our findings elucidate that stress concentrations between the σ and γ′ phases can be partially relieved by σ phase plastic deformation, reducing some adverse effects produced by the σ phase.