Influence of process parameters on microstructure and properties of Cu-Cr-Nb-Y alloy manufactured by laser powder bed fusion
(State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract: 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 (El) 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 El=0.375-0.538 J/mm. When El < 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 El 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 á110？ 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.
Key words: Cu-Cr-Nb-Y alloy; laser powder bed fusion; melt pool morphology; microstructure; mechanical properties