Optimization of conductivity and strength in Cu-Ni-Si alloys by suppressing discontinuous precipitation

Cu-Ni-Si alloys with and without Ti were solution treated at 980 A degrees C for 1 h and cooled by air cooling and water quenching, after which the specimens were aged at 500 A degrees C. The two alloys showed different aging characteristics with different cooling rates during the aging process. The conductivity of all alloys increased during aging; for alloys that were water quenched, hardness increased at the early stage of aging and then drastically decreased. The air-cooled Cu-Ni-Si alloy without Ti also experienced an increase in hardness, which then decreased during aging, but the air-cooled Cu-Ni-Si alloy with Ti did not show a drastic decrease in hardness during prolonged aging. A combination of yield strength and conductivity of 820 MPa and 42% IACS, respectively, was achieved in the air-cooled Cu-Ni-Si-Ti alloy after solution treatment.