Dependence of Interfacial Bonding Behavior on Strain Rate in Cocrfemnni High-Entropy Alloy Joints Produced by Vacuum Hot-Compression Bonding

Abstract

Vacuum hot-compression bonding (VHCB) is a highly competitive solid-state bonding technology. To expand the application prospects of VHCB in high-entropy alloys (HEAs), the interfacial bonding behavior of CoCrFeMnNi HEA VHCB joints was investigated, and its intense dependence on the strain rate was clarified. The microstructural characterization results suggested that excellent interfacial bonding was subject to interfacial grain boundary (IGB) migration and dynamically recrystallized (DRXed) grains, and exhibited different bonding behaviors at various strain rates. Interfacial residual nanoscale IOPs facilitated the nucleation of DRXed grains through particle-stimulated nucleation effect; however, their pinning effect on IGB migration also negatively affected interfacial bonding. In addition, this study focused on the prominent contribution of twin boundaries to IGB migration and revealed the evolution of interfacial microtexture. The tensile test results indicated that the ratio of joint elongation to base material elongation (REL) exhibited similar evolution characteristics to the interfacial DRX fraction (XDRX). A new interfacial bonding quality prediction model was developed by describing the quantitative relationship between REL and XDRX, and the accuracy of the model prediction was verified by comparing it with the tested values.

Keywords: high-entropy alloy, Vacuum hot-compression bonding, strain rate, Twin boundary, Dynamic recrystallization, Bonding quality prediction