Behaviors of Individual Dislocations in Cu-9 at % Al Alloys under Reverse Stress

Foil specimens prepared from bulk ones which were prestrained about 10 -1 in shear strain have been reversely loaded directly inside a 3MV-class electron microscope and associated behaviors of individual dislocations have been continuously observed. With increasing reverse stress from 0 to the prestress level, dislocation-structures such as widely spaced primary dislocations, dislocation pile-ups and Taylor type dislocation-dipoles decompose in sequence according to their mechanical stability. The highly stabilized dislocation-structures such as Taylor type dislocation-dipoles on closely spaced slip planes and heavily tangled dislocation-groups combined with different slip systems are retained even under the reverse stress higher than the prestress level.