Ce Effects on Deformation-Induced Microstructure Evolution in Cu-Ti-Ni-Mg Alloys

Cu-Ti-Ni-Mg and Cu-Ti-Ni-Mg-Ce alloys are prepared by vacuum induction melting. The hot deformation tests of the two alloys are carried out on the Gleeble-1500 simulator under the deformation temperatures of 550-950 degrees C and strain rates of 0.001-10 s(-1). The true stress-strain curves of the two alloys are obtained and the constitutive equations are established. The activation energy of the Cu-Ti-Ni-Mg alloy is 344.02 kJ mol(-1), and the activation energy of the Cu-Ti-Ni-Mg-Ce alloy is 389.87 kJ mol(-1). Based on the processing maps, the optimal processing parameters of the two alloys are obtained. The microstructure of the two alloys is analyzed by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The addition of Ce reduces the dislocation density and texture strength. The CuNi2Ti precipitates are found in both alloys, and there are more precipitates in the Cu-Ti-Ni-Mg-Ce alloys. The addition of Ce increases the flow stress and activation energy, promotes precipitation, and improves the deformation resistance of the alloys.