The transformation behavior of Cu–8.0Ni–1.8Si–0.6Sn–0.15Mg alloy during isothermal heat treatment

Abstract

Abstract The transformation behavior of Cu–8.0Ni–1.8Si–0.6Sn–0.15Mg alloy during isothermal heat treatment has been studied by transmission electron microscope observation. On the basis of micro-hardness measurement, time–temperature-property curves of the alloy have been established, and nose-temperatures of curves are about 650 °C. Discontinuous precipitates appeared as the samples isothermal heat treated at 550 °C, while continuous precipitates appeared as the samples isothermal heat treated at temperatures below 550 °C and above 650 °C. β-Ni3Si, δ-Ni2Si and δ′-Ni2Si precipitates were observed in the specimens. The crystal orientation relationships between copper matrix and precipitates were determined as ( 0 2 ¯ 2 ¯ ) Cu ‖ ( 0 1 ¯ 1 ¯ ) β ‖(010)δ, [100]Cu‖[100]β‖[001]δ; ( 0 2 ¯ 2 ¯ ) Cu ‖ ( 0 1 ¯ 1 ¯ ) β ‖(100)δ ′, [100]Cu‖[100]β‖[001]δ ′.