Copper–matrix composites reinforced with Al₂O₃, SiO₂, SiC and MgO nanoparticles were fabricated using powder metallurgy. The effects of the different nanoparticles on the thermal expansion behaviour of the composites were examined. The thermal expansion properties of the composites were evaluated using the coefficient of thermal expansion from 50 to 500°C. The relationship between interface stress and coefficient of thermal expansion of the copper–matrix composites with various reinforced phases was determined using theoretical models and experimental data. The results show that introducing dispersed nanoparticles into the copper matrix can significantly reduce the coefficient of thermal expansion. By contrast, increasing the temperature increases the thermal expansion coefficient of the copper–matrix composites and the interfacial pressure between the reinforcements and the copper matrix. The calculated pressure values at the nanoparticle–copper matrix interface suggest that plastic deformation occurred in the temperature range from 200 to 250°C for the SiO₂/Cu and SiC/Cu composites and at 350°C for the MgO/Cu and Al₂O₃/Cu composites. These values are consistent with the variations observed in the measured coefficient of thermal expansion.

Cu-Ni-Si alloys are widely used in lead frames and vacuum devices due to their high electrical conductivity and strength. In this paper, a Cu-Ni-Co-Si-Cr-(Ce) alloy was prepared by vacuum induction melting. Hot compression tests of the Cu-Ni-Co-Si-Cr and Cu-Ni-Co-Si-Cr-Ce alloys were carried out using a Gleeble-1500 simulator at 500–900 °C deformation temperatures and 0.001–10 s⁻¹ strain rates. The texture change was analyzed by electron backscatter diffraction. The fiber component dominated the texture after compression, and the texture intensity was reduced during recrystallization. Moreover, the average misorientation angle φ for Cu-Ni-Co-Si-Cr-Ce (11°) was lower than that of Cu-Ni-Co-Si-Cr (16°) under the same conditions. Processing maps were developed to determine the optimal processing window. The microstructure and precipitates of the Cu-Ni-Co-Si-Cr and Cu-Ni-Co-Si-Cr-Ce alloys were also analyzed. The average grain size of the Cu-Ni-Co-Si-Cr-Ce alloy (48 μm) was finer than that of the Cu-Ni-Co-Si-Cr alloy (80 μm). The average size of precipitates in the Cu-Ni-Co-Si-Cr alloy was 73 nm, while that of the Cu-Ni-Co-Si-Cr-Ce alloy was 27 nm. The addition of Ce delayed the occurrence of dynamic recrystallization.