Effects of Two-Stage Solution Heat Treatments on Microstructures and Properties of Cu-Cr-Zr Alloy

Novel two-stage solution heat treatments were applied to Cu-Cr-Zr alloy to improve its properties. The influences of these treatments on the microstructures and properties of the alloy were investigated by TEM, SEM, tensile testing and electrical conductivity test. The investigation showed that with the proposed solution treatments, it was possible to obtain better properties than the properties obtained by conventional single-stage solution treatment. For example, in the case of an alloy of Cu-0.4wt.%Cr-0.1wt.%Zr, it was found that a two-stage solution treatment system (8 h at 920 degrees C followed by 1 h at 1010 degrees C) produced better combination property than the conventional single-stage solution system (1 h at 950 degrees C) applied by other researchers. The first stage solution treatment is crucial to the dissolution of CuZr precipitates, dissolved CuZr phase completely, at the same time precipitated Cr phase. Subsequently, excess Cr precipitates all dissolved at the second stage solution treatment. As a result, a pure matrix is obtained after such two-stage solution heat treatments.