Tensile properties and work hardening in Al0.3CoCrFeNi: The role of L12 precipitates and grain size

Abstract

In this study, we investigate the FCC-Al_0.3CoCrFeNi high entropy alloy fabricated via spark plasma sintering of atomized powders, focusing on its mechanical and work-hardening properties across three distinct microstructures: coarse-grained, fine-grained, and fine-grained with L1₂ nano-precipitates. Using a dislocation density-based model, we analyze the effects of grain size and L1₂ precipitates on these properties, achieving quantitative agreement between model predictions and experimental tensile and work-hardening behaviors. This exploration highlights the underlying deformation mechanisms at room temperature and their contributions to the strength/ductility trade-off. Significantly, our analysis reveals that twinning in HEAs manifests differently from that observed in steels. Furthermore, the incorporation of L1₂ precipitates emerges as a critical factor enhancing the alloy's mechanical attributes. Our findings underscore the essential roles of microstructural parameters in tailoring the mechanical properties of HEAs, offering insights that could guide the design of advanced alloys with optimized performance.