Effect of Ni on Characteristics of Cu–Co–Si Alloy

Abstract

The effect of 0–0.5wt%Ni addition on recrystallization behavior during solution treatment at 825–1000°C, strength, electrical conductivity after aging at 475–600°C of Cu–1.0wt%Co–Xwt%Si–Ywt%Ni–0.15wt%Cr alloy （X＝0.28〜0.44, Y＝0〜0.5, （Co＋Ni）/Si≒3.4） was studied. The addition of Ni enhanced recrystallization temperature of the alloy. In the case of 0wt%Ni, recrystallization temperature was 825°C. In the case of 0.5wt%Ni, that was 950°C. On the other hand, electrical conductivity saturated at 950°C regardless of the concentration of Ni. Grain size at 950℃ was about 20μm regardless of the recrystallization temperature. The highest tensile strength after solution treatment at 950℃ and subsequent aging at 525°C was enhanced from 575 to 675 MPa as the concentration of Ni and Si increased. The increase of tensile strength was the result of the increase of （Co,Ni）Si precipitates. The electrical conductivity at 525℃ was lowered from 53 to 66%IACS. The tensile strength was more enhanced by cold rolling at 75% before aging. The electrical conductivity was slightly enhanced. The tensile strength＝about 700MPa, electrical conductivity＝59%IACS and MBR/t =0 were achieved by Cu–1.0wt%Co–0.33wt%Si–0.15wt%Cr–0.1wt%Ni alloy.