THE RELATION BETWEEN FLOW STRESS AND DISLOCATION STRUCTURE DURING RECOVERY OF HIGH-PURITY ALUMINUM,

Abstract : The flow-stress recovery of high-purity aluminum following a 10 pct tensile prestrain was studied in terms of a fractional flow-stress recovery parameter f sub r. The flow-stress recovery behavior was related to the dislocation arrangements using transmission electron microscopy. During recovery at 120 and 160 C, nearly stable strength levels were attained, the strength level for 120 C recovery being greater than that for 160 C. This stabilization of flow stress was related to the formation of metastable dislocation networks bounding nearly perfect cells. Both network formation and the annealing of dislocation loops were found to be recovery mechanisms, and the stronger metastable strength level for 120 C recovery was related to a smaller average cell size. Analysis of the networks was consistent with the reaction of sets of dislocations with a/2 (110) Burgers vector to give product Burgers vectors of either a/2 (110) or a (100). (Author)