Microstructure evaluation and resultant mechanical properties of laser- arc hybrid additive manufactured Cu-Cr-Zr alloy

Laser-arc hybrid additive manufacturing (LAHAM) of Cu-Cr-Zr alloy was studied. The microstructure evaluation and mechanical properties of the samples fabricated by LAHAM were analyzed compared with those prepared by wire arc additive manufacturing (WAAM). Columnar crystals growing along the building direction in both LAHAM and WAAM samples was observed. In the LAHAM sample, the grain size was refined and the maximum texture index and pole density intensity were reduced by 32.9% and 25.8% respectively compared with those in the WAAM sample. Meanwhile, it was found the uniform Cr precipitation, and the orientation relationship of precipitated Cr with Cu-matrix followed N-W relationship: (111) fcc.Cu // (110)bcc.Cr, [01̅1]fcc.Cu //[001]bcc.Cr, which was conducive to the improvement of tensile properties of the LAHAM copper alloy. Compared with the WAAM sample, the ultimate strength and elongation of LAHAM sample increased by 11.6% and 13.1%, to 258.7 MPa and 41.8%, respectively. The improvement in ultimate strength was attributed to grain refinement and precipitation strengthening, and it was found the precipitation strengthening accounted for about 75% of the total strength enhancement and was the primarily strengthening mechanism in the LAHAM copper alloy.