Selective laser melting of Al0.5CoCrFeNi high entropy alloy: Effect of heat treatment

The trade-off between strength and ductility has become a major bottleneck in the further development and practical application of materials. Metallic materials with high strength and sufficient ductility are usually the goal that is relentlessly pursued. The strategy of non-homogeneous microstructures provides a new direction to break through this bottleneck. In this study, dual-phase Al0.5CoCrFeNi high-entropy alloy (HEA) was fabricated using selective laser melting (SLM) technology with a striped 67 degrees interlayer rotation deposition strategy, and the effects of different heat treatment temperatures (800 degrees C, 900 degrees C, 1000 degrees C and 1100 degrees C) on their phase composition, microstructure and mechanical properties were investigated. The best overall properties were obtained for the alloys heat-treated at 1100 degrees C (YS of about 600 MPa, UTS of about 1.1 GPa and EL of about 25 %). The excellent tensile mechanical properties of the alloys are attributed to the dual non-uniform microstructure with different characteristics of Nanoscale precipitation phase and local recrystallisation, which endows the alloys with different main sources of strengthening at different heat treatment temperatures. The material properties can be optimized by tailoring the microstructure.