RECRYSTALLIZATION MECHANISMS IN A CU-CR-ZR ALLOY WITH A BIMODAL DISTRIBUTION OF PARTICLES

The influence of the initial particle distributions on the recrystalli zation kinetics of a copper alloy containing two types of particles wa s studied. Comparisons were made between the softening rates during is othermal anneals at temperatures ranging between 500 degrees C and 700 degrees C. Microstructural studies of annealed bulk samples were carr ied out by scanning and transmission electron microscopies. The mechan ism of grain formation seems to be independent of the particle distrib ution and involves reorientation of the deformation cells into subgrai ns and into well defined grains by rearrangement of dislocations in th e cell walls. The mechanism of recrystallization can be seen as a comp romise between the differing behaviours of fine and coarse dispersoid particles of the alloys, in which recrystallization is initiated at la rge particles for sufficiently high temperatures, but is gradually sup pressed by the influence of the fine particles as the annealing temper ature is decreased.