Effects of Y addition on the microstructure, properties and softening resistance of Cu-Cr alloy

The effects of Y content on the microstructure and properties of Cu-0.9Cr and Cu-1.45Cr alloys were investigated systematically in present manuscript. Cu-Cr-(Y) alloys were prepared by vacuum melting and casting, solid solution treatment at 960 degrees C, (90% cold rolling) and aging treatment at 460 degrees C. The results indicate that the addition of 0.1 wt% Y refines the eutectic structure of as-cast Cu-0.9Cr and Cu-1.45Cr alloys. Besides, the hardness of Cu-Cr-(Y) alloys after solid solution treatment increases with the increase of the Y content. CRA (cold-rolling and aging) process can enhance the hardness of peak-aged alloys compared with SSA (solid solution and aging), the peak-aged hardness and corresponding conductivity of cold-rolled alloys slightly increase by addition of Y. Especially, when CRA for 300 min, the ultimate tensile strength, hardness of Cu-0.95Cr-0.1Y alloy (433 MPa, 146.8 HV) are superior to those of Cu-0.9Cr alloy (333 MPa, 102 HV), indicating that addition of Y significantly inhibits the over-aging during CRA. The TEM results reveal that Cr precipitates of FCC and BCC structures exist in the Cu-Cr-Y alloy aged for 300 min, and Y element suppresses the coarsening of Cr precipitates and the reduction of dislocation density. Moreover, the softening temperature of peak-aged Cu-Cr-Y alloys is similar to 70 degrees C higher than that of Cu-Cr alloys since the addition of Y inhibits the coarsening of Cr precipitates. (C) 2022 Elsevier B.V. All rights reserved.