Precipitation in a Cu- Cr- Zr- Mg alloy during aging

The precipitation processes in a Cu-0.69Cr-0.10Zr-0.02Mg alloy aged at 450 degrees C and 550 degrees C have been investigated by transmission electron microscopy and high resolution transmission electron microscopy. The precipitation sequence in this alloy aged at 450 degrees C is: supersaturated solid solution -> Guinier-Preston zone (fcc Cr-rich phase) -> ordered fcc Cr-rich phase -> ordered bcc Cr-rich phase. The precipitation sequence in this alloy aged at 550 degrees C is: supersaturated solid solution -> ordered fcc Cr-rich phase -> ordered bcc Cr-rich phase. In the evolution of decomposition, the orientation relationship between the precipitates and the Cu matrix changes from cube-on-cube to Nishiyama-Wassermann orientation. The ordering of Cr-rich precipitates facilitates the formation of the bcc precipitates and promotes the development of Nishiyama-Wassermann orientation. (C) 2013 Elsevier Inc. All rights reserved.