AGING CHARACTERISTICS OF CU CR IN-SITU COMPOSITE

The ageing behaviour of a Cu-15 wt% Cr in-situ composite was investiga ted systematically by means of hardness testing, electrical conductivi ty measurement, scanning electron microscopy, analytical transmission electron microscopy and high-resolution electron microscopy. The mater ial was found to have a peak hardness after ageing at around 773 K and a peak electrical conductivity at around 873 K. In contrast with the dilute Cu-Cr alloys, Cr-rich clusters were observed at the early aged condition in the Cu matrix, which matches not only the results of mech anical and physical property measurement but also the theoretical pred iction. In addition, the precipitates at peak hardened condition in th e Cu matrix were determined to be Cr Guinier-Preston zones. Cr ribbon as the in-situ reinforcing element shows no measurable ageing effect d ue to the high-temperature solution treatment. (C) 1998 Chapman & Hall .