Microstructure evolution and properties of multi-scale precipitate strengthened Cu-Cr-Nb alloy

Cu-Cr-Nb alloys has become a key material for ITER plasma facing components (PFC) due to its excellent thermal stability. In this study, Cu-3.3Cr-1.6Nb (wt%) alloy was prepared through in-situ casting using Cu-Cr and Cr-Nb master alloy. The agglomeration and coarsening of Cr2Nb particles in Cu-Cr-Nb alloy are improved. The effect of aging temperature on the microstructure and properties of rolled Cu-3.3Cr-1.6Nb alloy. The results show that the aged Cu-3.3Cr-1.6Nb alloy contains multi-scale precipitation phases distribution with micron-level Cr2Nb (0.2-2 mu m), Cr-rich phase (2.2 mu m), nano-level Cr2Nb (13.1 nm) and nano-level Cr (9.3 nm). After aging at 450 degrees C for 0.5 h, the tensile strength and electrical conductivity of the aged alloy were 469 MPa and 78.5% IACS, respectively. According to TEM and EBSD analysis, the Cr2Nb particles did not grow during the aging and were pinned the grain boundaries to inhibit the growth of Cu matrix grains, which result in a good thermal stability of Cu-3.3Cr-1.6Nb alloy. This study provides a new method for preparing Cu-Cr-Nb alloy with high-strength, high-conductivity and high heat resistance by casting method.