Micro-laminated CoCrFeMnNi−TiNp/CoCrFeMnNi high-entropy alloy matrix composite with bimodal grain structure via multi-material selective laser melting (MM-SLM) additive manufacturing

Abstract

Deviating from most studies on selective laser melting (SLM) additively manufactured single metals or homogeneous metal matrix composites (MMCs), this work engaged in a multi-material SLM (MM-SLM) route for micro-laminated MMCs with bimodal grain structures. Structurally hierarchical micro-laminate of CoCrFeMnNi high-entropy alloy (HEA)-based HEA−TiNp/HEA MMC was built by the MM-SLM to overcome the strength-ductility trade-off and improve the anti-impact performance under high strain-rate compression deformation. The dynamic impacts were performed on the SLM-built HEA and MM-SLM-built HEA−TiNp/HEA using a split Hopkinson pressure bar (SHPB) system, with the strain rates of 1000 s−1, 2000 s−1, and 3000 s−1. The structurally hierarchical HEA−TiNp/HEA exhibited higher strength and deformability than the HEA. The strain-rate-dependent work hardening capacity and macroscopic plasticity of the HEA−TiNp/HEA indicated a better resistance to dynamic shocks. The promising results pave a road for achieving high-performance HEA-based MMCs of the MM-SLM-built hierarchical structures with a relatively low proportion of nano-ceramic reinforcements and bimodal-grained HEA matrix.