Effects of grain size and thickness on creep deformation of aluminium thin foils with meso-scale

Constant stress creep experiments were carried out at 200°C for aluminium thin foils with a thickness range of 10-350μm. The effects of the thickness (t) and the grain size (d) on the strain rate (Ε) were studied and the parameter, t/d, can better describe those effects. Subgrains were found near the grain boundary by TEM in the deformed specimen with t/d n (t/d)1.95, n = n′-0.815ln (t/d), n′ is the stress exponent of the block meterial, was obtained to describe the relation of t/d to Ε, which basically depended on the ratio of grain boundary area to the free boundary area.