Microstructure and mechanical properties of Cu-Cr-Zr alloy prepared by electron beam additive manufacturing and laser-MIG hybrid welding

Cu-Cr-Zr alloys are widely used as medium-strength and high-conductivity copper alloys in aerospace, transportation and electronic information fields. The application of additive manufacturing technology is expected to realize the preparation of Cu-Cr-Zr alloy parts with complex structure and superior property. However, the commonly used laser additive manufacturing technology is not applicable to the preparation of copper alloys due to its intrinsic high reflection to laser. In this study, we adopted two technologies, i.e., electron beam additive manufacturing (EBAM) and laser-metal inert gas hybrid welding (laser-MIG), for the preparation of Cu-Cr-Zr alloys. Finite element simulation was employed to simulate the temperature field and residual stress field of the material during solidification. The microstructure, relative density, microhardness, tensile properties and electrical conductivity of the as-fabricated samples were characterized. The results showed that samples with better moldability were obtained by both methods at a line energy density of 600 J/mm. In the top area, both methods exhibit medium-sized equiaxed grains with more precipitated phases, showing the best comprehensive properties. The EBAM method demonstrates superior formability, better relative density and electrical conductivity due to more stable temperature field changes. On the other hand, the laser-MIG method obtains finer grains and higher mechanical properties because of a faster cooling rate, but leads to a decrease in relative density and electrical conductivity. This study presents new experimental data for Cu-Cr-Zr alloys prepared by EBAM and laser-MIG methods, contributing to extend the application of additive manufacturing in the preparation of Cu alloys.