Effect of heat treatment on the microstructure and properties of CuCrZr alloy manufactured by wire arc additive manufacturing

Heat treatments have a significant effect on the properties of CuCrZr alloy. However, the mechanism of how heat treatments affect the microstructure and properties of CuCrZr alloy remain unclear during wire arc additive manufacturing (WAAM). Achieving the preparation of CuCrZr alloy with excellent performance by WAAM presents a challenging task. This study investigated the evolution of the microstructure, mechanical properties, electrical and thermal conductivities of CuCrZr alloy specimens fabricated by WAAM under different heat treatments. Microscopic analysis results illustrate that the specific heat treatments do not lead to significant changes in grain morphology, but can affect the formation of precipitation in CuCrZr alloy. The coarse Cr pre-cipitation is observed in the specimens of as-built (AB) and direct age hardening (DAH). Conversely, the solution annealing (SA) and solution annealing + age hardening (SAAH) specimens exhibit a uniform distribution of Cr elements without coarse Cr precipitation. Notably, in the SAAH specimen, the relationship between precipitated Cr and Cu matrix follows the K-S relationship: (111)Cu//(110)Cr, [110]Cu//[111]Cr, leading to a significant improvement in mechanical properties. The SAAH specimen demonstrates the best performance among all the specimens. It exhibits the an ultimate tensile strength of 301 & PLUSMN; 5 MPa, the highest hardness of 119.5 & PLUSMN; 2.4 HV, electrical conductivities of 45.8 & PLUSMN; 0.1MS/m and thermal conductivities of 309.2 & PLUSMN; 2.0 W/mK. This superior performance can be attributed to the combination of minimal lattice distortion and uniformly fine Cr precipi-tation in the SAAH specimen.