Microstructure evolution in Cu-Ni-Co-Si-Cr alloy during hot compression by Ce addition

Abstract

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 <110> fiber component dominated the texture after compression, and the texture intensity was reduced during recrystallization. Moreover, the average misorientation angle ψ 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.