High Temperature Deformation And Age Hardening Behaviors Of Cu-1.0Zr(-RE) Alloys

The thermal simulation test of Cu-Zr alloy with Zr content of 1% is carried out by Gleeble-1500 D thermal simulation tester.The variation law of flow stress is studied.The activation energies and constitutive equations of the alloy are obtained by the correlation among flow stress,strain rate and deformation temperature.The influence of rare earth elements on the thermal activation energy of the alloy is analyzed.The dynamic recrystallization evolution mechanism of the alloy during high temperature thermal deformation is observed by optical microscope and transmission electron microscope.The aging of the alloy after the solution are carried out in different degrees of cold deformation,and then aging treatment at 400-550 ?.The change of the electrical conductivity and microhardness are analyzed,and the change process of the precipitate phase during the alloy aging process is studied.The aging strengthening mechanism and aging precipitation kinetics of the alloy are discussed.The results show that Cu-1.0Zr(-RE)alloy have different thermal deformation mechanism at different temperatures,it has a typical dynamic recovery characteristic at 550-750 ?,and it has dynamic recrystallization thermal deformation characteristics850-900 ?.Compared with the pure copper heat compression process,the hot deformation activation energy of Cu-1.0Zr alloy is increased by 54% with adding Zr.Compared with the Cu-1.0Zr alloy heat compression process,the hot deformation activation energy is respectively increased by 18% and 34% with adding Y and Ce.Increasing temperature and decreasing strain rate are favorable to the occurrence of dynamic recrystallization.The addition of rare earth elements can refine the grain and promote the dynamic recrystallization.The optimum processing area of Cu-1.0Zr alloy is 770-900 ? and strain rate 0.001-0.1 s-1.During the initial stage of aging,the precipitates gradually increased,and over the aging,the precipitate phase became coarse and appeared to be dissolved.Cu-1.0Zr(-RE)alloy after 60% cold deformation,at 500 ? aging for 1 h can get the best comprehensive performance.Cu-1.0Zr alloy at500 ? aging for 1 h peak state,the coherent strain enhancement is the main reason for its strength increase.The intrinsic kinetic equation and the conductivity equation of the alloy at 550 ? are deduced by the Avrami equation,which can reflect the change of the conductivity with the aging time and can reflect the phase transition process.The addition of rare earth elements improves the microstructure of the alloy,slightlyreduces its conductivity,and has little effect on the aging kinetics S curve.