Influence of process parameters on microstructure and properties of Cu−Cr−Nb−Y alloy manufactured by laser powder bed fusion

A novel Cu−4.8Cr−2.2Nb−0.15Y (at.%) alloy was fabricated by employing the laser powder bed fusion with different processing parameters. The influence of laser power (P), scanning speed (v), and laser linear energy density (E_l) on the defects, melt pool morphology, microstructure, and properties of the alloy was systematically investigated. The results show that the optimized process parameters for preparing Cu−Cr−Nb−Y alloy with relative density over 99.5% are P=300−350 W and v=650−800 mm/s, corresponding to E_l=0.375−0.538 J/mm. When E_l < 0.3 J/mm, increasing P or decreasing v can enhance the continuity and size of the melt pool, reduce the lack-of-fusion defects, and increase the relative density. However, excessively high E_l leads to a deeper melt pool, more keyholes, and reduced relative density. The grain size of the as-built Cu−Cr−Nb−Y alloy shows a bimodal distribution, with fine grains at the center and coarse grains at the edge of the melt pool. Increasing P or decreasing v increases the average grain size and 〈110〉 texture intensity. The alloy fabricated with P=350 W and v=800 mm/s displays the highest relative density of 99.82%. The yield strength, tensile strength, and elongation are (443±5) MPa, (699±4) MPa, and (17.1±0.7)%, respectively.