Effect of temperature on the mechanical properties of Ni-based superalloys via molecular dynamics and crystal plasticity

Abstract

Study on the influence of temperature on the mechanical properties across multiple scales has been a focus on the research of Hastelloy-X (HX) alloys for the application in high-temperature structure components. In this work, Molecular Dynamics (MD) and Crystal Plasticity (CP) are put together to solve it from atomic scale to mesoscopic scale. MD research indicates that the deformation of HX alloy occurs in two stages at temperature below 300 K: initially, as stacking fault deforms, stacking fault can transform into twinning with increasing strain. When the temperature exceeds 300 K, deformation primarily forms a stacking fault. The twinning deformation path transforms from intrinsic stacking fault to extrinsic stacking fault and then to twinning. A mesoscopic-scale CP model was developed using atomic-scale deformation mechanisms to bridge the gap between deformation mechanisms and experimental results. The CP results indicate a functional relationship between the strength of HX alloy and temperature. This relationship appears insensitive to crystal texture and grain shape. Incorporating grain morphology and texture into the model significantly impacts the strength response of calculating HX alloy. After the tensile deformation of HX alloy at 300 and 1173 K, the atomic scale deformation results characterized by transmission electron microscopy are aligned with the MD simulation results. The relationship between strength and temperature predicted by CP results has also been validated. A thorough investigation into the deformation behavior of HX alloys across different scales, employing MD and CP models, introduces a novel approach for predicting the mechanical properties of superalloys.