CREEP TRANSIENTS DURING STRESS CHANGE TESTS IN AN Al-0. 25 WT% Li ALLOY AT 200 degree C.

Both unloading and reloading experiments were performed on an Al-0. 25 wt% alloy crept at 200 degree C. Smooth transients were observed in all cases and incubation periods or delay times were not observed. Large anelastic instantaneous strains occur on both unloading and reloading. The reloading strains depend on the time of unloading and the stress reduction, and are inconsistent with those expected from the network theory of recovery-controlled creep. The results are discussed in terms of published information on dislocation motion in pure Al and Al alloys