Analysis and development of CuCrZr alloy fabrication in LPBF: Impact of process parameters and heat treatments on thermo-mechanical properties

This study explores the manufacturing and characterization of CuCrZr alloy using the Laser Powder Bed Fusion (LPBF) process, focusing on the optimization of process parameters and the impact of heat treatments on the thermo-mechanical properties. The research demonstrates the feasibility of producing dense using a low-power LPBF machine, achieving a relative density of 99.75 % through process parameter tuning. Two heat treatments have been tested, the standard Solution Annealed and Age-Hardened (SA+AH) heat treatment and the Direct Age-Hardened (DAH) heat treatment, both of which produce metallic chromium precipitates that enhance the material's conductivity and mechanical properties. The as-built (AB) parts exhibit a unique microstructure, characterized by columnar grains and minimal lack of fusion porosities, which remains unchanged with the DAH heat treatment. However, annealing the material partially recrystallizes the microstructure, resulting in larger grains and lowering the mechanical strength of the material. Specifically, the DAH heat treatment resulted in a yield strength that was doubled and an Ultimate Tensile Strength (UTS) that was 40 % higher compared to the solution annealed parts. The SA+AH heat treatment results in partial recrystallization of the microstructure, which makes the material more ductile. This increases the material's thermal and electrical conductivity, although to a lesser extent than the DAH heat treatment. The study concludes that directly ageing an LPBF part is the optimal choice to achieve an excellent combination of high mechanical strength and high thermal and electrical conductivity.