Precipitation behavior of supersaturated solid-solubility CuCrZr alloy by additive manufacturing

Abstract

As a typical precipitation-strengthened alloy, the improvement of CuCrZr alloy performance can be achieved by promoting the precipitation of alloying elements. However, the low solubility of Cr limits further enhancement of the performance of conventionally processed CuCrZr alloys. In this study, a supersaturated solid solution CuCrZr alloy was prepared using laser powder bed fusion (LPBF), and the precipitation of solute atoms was promoted through heat treatment, resulting in an alloy with excellent comprehensive performance. The influence of different heat treatment processes on the precipitation behavior and performance of the alloy was investigated. Microstructural analysis revealed the presence of micrometer-scale Cr particles in the specimens after solution treatment (ST) and solution-aging treatment (SAT), while the direct-age-hardening (DAH) specimen exhibited dispersed nanoscale Cr precipitations. Notably, a Nishiyama-Wassermann (N-W) relationship was observed between the Cr precipitations and the Cu matrix, significantly enhancing the mechanical properties of the alloy. The DAH specimen exhibited an ultimate tensile strength (UTS) of 661.54 MPa, a hardness of 231.03 HV and an electrical conductivity of 65.05 % IACS, demonstrating the best match between mechanical properties and electrical conductivity. The outstanding properties can be credited to the uniformly distributed Cr nano-precipitates and slim lattice distortion. Additionally, the main strengthening mechanism is precipitation strengthening for CuCrZr alloy.