Tensile Deformation Behaviors of Ultra-Fine Subgrained Aluminum
Tensile deformation behaviors up to peak stress of the ultra-fine subgrained aluminum (2024Al) with the subgrain sizes of about 250 nm and low dislocation density inside were investigated. The results show that the ultra-fine subgrained aluminum exhibited high strain hardening and large uniform plastic strain (19.3 %), but little post-deformation hardness/dislocation density increases (99.6 HV vs. 100.3 HV and 0.79×1014 m-2 vs. 1.03×1014 m-2, respectively). The theoretical calculation based on Taylor equation demonstrated that the dislocation density increase during the tensile deformation up to peak stress was very enormous (1.64×1015 m-2). These results not only implied that the dislocations involved in the tensile deformation were in large quantities but most of them disappeared upon the unloading of the tensile deformation, but also demonstrated that high strain hardening capacity is not a sufficient factor for ultra-fine subgrained metals to store deformation dislocations leading to post-deformation hardness increases.
X. J. Xu et al., "Tensile Deformation Behaviors of Ultra-Fine Subgrained Aluminum", Materials Science Forum, Vol. 683, pp. 189-192, 2011