Microstructure and mechanical properties of Al0.5CoCrFeNi HEA prepared via gas atomization and followed by hot-pressing sintering

Abstract

Pre-alloyed Al0.5CoCrFeNi high-entropy alloy (HEA) powders were prepared via gas atomization and followed by hot-pressing sintering (HPS) at 1200 °C for 1 h to fabricate bulk materials. The phase stability, microstructure evolution and mechanical properties of Al0.5CoCrFeNi HEA were mainly investigated. Results indicated that the atomized powders exhibited a fine-grained FCC + dendritic-like ordered BCC (B2) dual-phase structure. Rapid solidification was favorable to the metastable B2 phase formation during gas-atomization. Partial of the dendritic-like B2 phase dissolved after annealing (>600 °C), resulted in a homogeneous dual-phase structure with irregular B2 phase dispersed in the FCC matrix. The homogeneous structure was “inherited” in the sintered bulks and coarsened after HPS. Tensile test results suggested that the sintered bulks possessed excellent comprehensive mechanical properties with yield strength, ultimate tensile strength and elongation of 587.3 ± 18.7 MPa, 960.2 ± 23.6 MPa and 32.6 ± 5.1%, respectively. The excellent mechanical response during deformation was mainly attributed to the synergistic deformation of the FCC/B2 phase and considerable back stress hardening mechanism.

Keywords

• Gas-atomized
• High entropy alloy
• Dual-phase
• Phase transition
• Mechanical properties