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

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 degrees C. Discontinuous precipitates appeared as the samples isothermal heat treated at 550 degrees C, while continuous precipitates appeared as the samples isothermal heat treated at temperatures below 550 degrees C and above 650 degrees C. (beta-Ni(3)Si, delta-Ni(2)Si and delta'-Ni(2)Si precipitates were observed in the specimens. The crystal orientation relationships between copper matrix and precipitates were determined as (0 (22) over bar)(Cu)parallel to(0 (11) over bar)(beta)parallel to(010)(delta), [100](Cu)parallel to[100](beta)parallel to[001](delta); (0 (22) over bar)(Cu)parallel to(0 (11) over bar)(beta)parallel to(100)(delta)', [100](Cu)parallel to[100](delta)'. (c) 2011 Elsevier Inc. All rights reserved.