Tuning the mechanical properties of AlCoCrFeNi2.1 laser-welded joints through aging heat treatment

Herein, the aging heat treatment was employed to optimize the microstructure and mechanical properties of the AlCoCrFeNi_2.1 laser-welded joints. Microstructural and mechanical characterizations of the as-welded and as-aged samples were conducted via X-ray diffraction, thermodynamic calculation, electron backscattered, and transmission electron microscopy. Tensile testing results of the as-aged AlCoCrFeNi_2.1 welded joints, when compared to as-welded counterparts, indicate that aging heat treatment enhances tensile strength with a minimal compromise in the elongation. Subsequent in-depth exploration into the strengthening mechanism uncovers that grain refinement and precipitation strengthening are primarily responsible for the improvement in the strength, with a minor decreased contribution from dislocation strengthening. The determined tensile properties of the as-welded, as-aged 6h, and as-aged 8h samples are 836.52 MPa, 905.73 MPa, 969.99 MPa of yield strength, 1188.14 MPa, 1276.90 MPa, 1481.60 MPa of ultimate tensile strength, with an elongation of 11.06 %, 9.63 %, and 9.17 %, respectively. These outcomes demonstrate the achievement of an optimal balance between strength and plasticity.