Precipitation characteristics of Cu–15Cr–0·15Zrin situcomposite

The precipitation characteristics of Cu–15Cr–0·15Zr in situ composite made by cold drawing have been studied using analytical TEM and hardness measurement. It has been observed that the in situcomposite reaches peak hardness at a lower aging temperature than the corresponding alloy which is not subjected to cold working prior to aging treatment. The Cr rich precipitates in the peak aged composite are much smaller than those in the peak aged alloy. Under peak aging conditions, precipitation free zones adjacent to the grain boundaries of the Cu matrix are also observed in both the alloy and the composite. The addition of Zr enhances the precipitation hardening effect in the alloy and the composite. The major mechanism of this enhancement may be through increasing the Cr rich precipitate nucleation rate and precipitate/matrix interfacial energy.