Influence of Pre-annealing Temperature on Microstructure Evolution and Mechanical Properties of Semi-solid Copper Alloy Billet

The as-cast CuSn10P1 copper alloy was pre-annealed and then prepared into semi-solid billets by cold rolling isothermal treatment strain-induced melting activation (CRITSIMA) method. The effects of pre-annealing temperature on the microstructure evolution and mechanical properties of semi- solid copper alloy billets were studied by OM, SEM, EDS, XRD, electron probe and Brinell hardness analyses. The results show that with increasing the pre-annealing temperature, the average grain size of the semi-solid copper alloy billet is increased, and the shape factor and liquid phase ratio are decreased. With increasing the pre-annealing temperature, Sn element content is increased in the solid solution of a-Cu phase, segregation of Sn element is weakened, the content of intergranular brittle and hard phase d is phase decreased, and the Brinell hardness is gradually decreased. The new phase Cu13.7Sn is detected in the semi-solid copper alloy billet, which is related to the high segregation of the intergranular Sn element. The semi-solid copper alloy billet prepared by pre-annealing at 600. for 2 h has fine and uniform microstructure and good mechanical properties. The average grain size is 68.34 mu m, the shape factor is 0.78, and the Brinell hardness is 1254.4 MPa.