Microstructure evolution and properties of Cu-Cr alloy during continuous extrusion process

The microstructure evolution and properties of a typical precipitation strengthened Cu-0.82Cr alloy during continuous extrusion were investigated by means of optical microscopy, transmission electron microscopy, hardness and conductivity measurement. The severe plastic deformation and precipitation behavior of the alloy during deformation were discussed in detail. The results showed that hardness increased firstly until reaching the maximum value of 148 HB in right-angle bending, and then decreased in the extending extrusion zone. Severe deformation and precipitation process occurred during continuous extrusion, and the nano-scale precipitates inhibited the recrystallization in some extent, both of which contributed to the properties of the extruded alloy. The extruded alloy had an average grain size of about 1.5 μm, and it reached a yield strength, ultra-strength, elongation and electrical conductivity of 292 MPa, 346 MPa, 34% and 77.5%IACS, respectively. •Maximum Hardness appears in right-angle bending.•Recrystallization and precipitation process occur during the continuous extrusion.•Precipitates have a serious interaction with the dislocations during deformation.•Nano precipitates and fine grain size contribute to good properties of the alloy.