Ceramic Particle-Reinforced Medium-Entropy Alloys With Outstanding Mechanical Properties Prepared by Novel Micro-LPBF

Additive manufacturing of multi-principal element alloys is a promising approach for fabricating functional materials. A medium-entropy alloy (MEA) composite was fabricated using micro-scale laser powder bed fusion (µ-LPBF) with nano-ceramic particle doping, exhibiting a notable strength-ductility synergy. The microstructural evolution, mechanical properties, and deformation mechanisms of the composite were systematically investigated. The unique µ-LPBF process and subsequent aging treatment enabled the composite to exhibit good properties, including high hardness (557.5–789.1 HV), excellent tensile strength (1675 MPa), and uniform elongation (28%). Furthermore, the tensile strength was increased to 1817 MPa via ceramic particle doping, without compromising the ductility at 18%. Ultra-high temperature gradients and cooling rate in µ-LPBF are conducive to grain refinement and the simultaneous activation of multiple strengthening mechanisms, thereby enhancing strain-hardening and ductility. The enhanced performance of the MEA, including tensile strength, corrosion resistance, and wear resistance arise mainly from synergistic multi-level microstructures, featuring segregation-induced dislocation banding, ultrafine γ′ precipitates, Cr-rich σ-phase precipitates with controlled fraction and morphology, dense 9R phase, high-density dislocations, dense nanotwin/microband networks, Lomer-Cottrell locks, and related crystallographic defects. The novel alloy design, combined with a streamlined, optimized processing strategy, plays a crucial role in developing multi-component alloys and composites with outstanding mechanical properties.