Temperature-dependent deformation mechanisms and quantitative strength analysis of a Ni-based superalloy with bimodal precipitation distribution

Ni-based superalloys are essential for high-temperature applications in aerospace, yet their mechanical properties are intricately linked to the size distribution of γ′ precipitations. The purpose of this study is to investigate the relationship between γ′ precipitation and alloy deformation mechanism by analyzing the tensile behavior of Waspaloy with bimodal size distribution at different temperatures, which is the key to optimize the properties of aeroengine alloys. Through a series of tensile tests from room temperature (RT) to 800 °C, combined with microstructure characterization, it found complex intensity trends with temperature, including Portevin-Le Châtelier (PLC) effect at 400 °C and double yielding phenomenon at 800 °C. The critical shear stress (CRSS) was analyzed quantitatively, and the effect of γ′ precipitations on dislocation behavior was revealed. The relationship between precipitation size and deformation behavior was quantified. The results show that yield strength can be predicted accurately and is significantly affected by precipitation characteristics, thus deepening people's understanding and providing a new perspective for deformation mechanism of superalloys. This indicates that the high-temperature properties of Ni-base superalloys can be improved and effectively by adjusting the heat treatment parameters to control the precipitation state.