Low-temperature creep mechanism in ultrafine-grained aluminum

This study investigated the low-temperature creep mechanisms in ultra-fine grained aluminum made by accumulative roll bonding. The low-temperature creep behaviors in ultra-fine grained aluminum with grain size of 0.39 µm were divided into four regions by three certain stress values, σmy, σmulti and σy. σmy is stress for dislocation movement, σmulti is stress for dislocation multiplication, and σy is yield stress. First, below σmy, plastic deformation was negligible. Second, from σmy to σmulti, creep deformation with n=2.5 occurred by grain boundary sliding. Third, from σmulti to σy, creep deformation with n=7.2 occurred by intragranular recovery of dislocations. Last, above σy, power-law breakdown was confirmed.