Microstructure and strengthening mechanisms of CuCrZr alloy by two-step thermomechanical treatment

The high strength obtained in Cu-Cr alloys is mainly attributed to the precipitation strengthening, dislocation strengthening, and grain-boundary strengthening. The precipitate size, dislocation density, and grain size are related to thermomechanical treatment. The strength of Cu-Cr alloys can be controlled by the thermomechanical treatment process. In this study, the microstructure and strengthening mechanisms of Cu-0.8Cr-0.1Zr (wt%) alloy after one-step and two-step thermomechanical treatment were studied. The results showed that after the following thermomechanical treatments, solution treated at 950 degrees C for 60 min, thickness reduction at first cold rolled for 60%, annealed at 450 degrees C for 180 min, and then 30% thickness reduction in secondary cold rolling, the microhardness, tensile strength, and conductivity reach 215 HV, 623 MPa, and 74.5% IACS, respectively. The main difference of strength between one-step and two-step thermomechanical treatment in the Cu-0.8Cr-0.1Zr alloy is due to the difference of dislocation strengthening effect. The dislocation strengthening achieved in two-step thermomechanical treatment (175.6 MPa) is 95 MPa greater than that of one-step thermomechanical treatment (80.6 MPa).