Microstructure and mechanical performances of NiCoFeAlTi high-entropy intermetallic reinforced CoCrFeMnNi high-entropy alloy composites manufactured by selective laser melting

Abstract

Multi-component alloys have been confirmed to be excellent reinforcing phases in high-entropy alloy-based composite. However, achieving a balance between strength and ductility by controlling the reinforcement content remains a major challenge in the design of high-entropy alloy-based composites. In this study, CoCrFeMnNi HEA/NiCoFeAlTi HER high-entropy alloy composites were prepared using SLM technology. Interestingly, gas-atomized NiCoFeAlTi high-entropy intermetallic (HER) powder was selected as the reinforcing phase, and the CoCrFeMnNi HEA matrix was used for comparison. The influence of the reinforcement content on the composite was investigated, and high-performance HEA/HER composites were obtained, with the strengthening mechanism elucidated. The results showed that the composite with 1 wt% HER reinforcement exhibited the optimal performance, with hardness, yield strength, ultimate tensile strength, and ductility at room temperature being approximately 226.9 HV, 562 MPa, 683 MPa, and 16%, respectively. The excellent mechanical properties at both room and elevated temperatures are attributed to the synergistic effects of heterogeneous microstructure strengthening, grain refinement, and precipitation strengthening. This work provides a foundation for the development of high-entropy alloy composites reinforced by high-entropy intermetallics.

Keywords

• Selective laser melting
• CoCrFeMnNi composites
• High entropy intermetallics
• Microstructure
• Mechanical properties
• Strengthening mechanism