Fabrication of gradient-structure CuNiBe alloy bars by laser remelting and water-cooling

Abstract

ABSTRACTLaser remelting (LR) is a typical laser manufacturing technique. In this study, LR was used to fabricate gradient-structured CuNiBe alloy bars. A series of LR experiments with different parameters (such as the output power of the laser transmitter, scanning speed, and cooling condition) and subsequent aging treatments were designed. The remelted zone depth (RZD), the hardness with depth on the plane perpendicular to the LR track, the microstructure, and the precipitation characteristics of different zones of the remelted samples were analyzed. The results showed that the RZD increased with a higher output power of the laser transmitter and lower scanning speed. The hardness of the CuNiBe was significantly improved by the LR and subsequent aging treatment. A remelted zone (RZ) and heat affected zone (HAZ) were found in the remelted surface layer, and equiaxed substructures and columnar substructures were present in the RZ. Well-dispersed NiBe precipitates on the substructure boundaries in the transitional area between the RZ and HAZ were the main cause of strengthening of the sample that underwent LR without water-cooling. The strengthening effect was significantly enhanced by the refined grains for the sample that underwent LR with water-cooling.