ISOTROPIC AND KINEMATIC HARDENING IN A DISPERSION-STRENGTHENED ALUMINUM-ALLOY

The room temperature mechanical behavior of a dispersion strengthened aluminum alloy was examined in tension, compression, and in fully reve rsed loading. The alloy, 8009, is characterized by a high volume fract ion of 50-100 nm dispersoid (25%) and 0.5 mm grain size. In tension, 8 009 exhibits low strain to UTS and large post uniform elongation; in c ompression, near steady state deformation is observed after 2-3% strai n. The Bauschinger effect was quantified as a function of prestrain in the forward direction. The experimental reverse loading curves were c ompared to those expected for ideal isotropic hardening and ideal K1 t ype kinematic hardening. The alloy exhibits nearly pure kinematic hard ening of the K1 type. Based on the microstructure and the fully revers ed loading behavior, the monotonic deformation behavior is explained.