A multi-scale Al-Mg alloy containing ultra-fine lamellar structure

This paper reports a study on multi-scale metallic materials containing ultra-fine lamellar structure, which have received very limited attention in the published literature. In the present study, a multi-scale Al-Mg alloy, which comprises ultra-fine lamellar structure with a high density of dislocations, as well as nearly dislocation-free equiaxed ultra-fine, fine and coarse grains, was produced via partial recrystallization of the heavily cold-rolled coarse-grained (CG) counterpart. The multi-scale Al-Mg alloy achieves both high strength (~320 MPa in 0.2% offset yield strength in comparison with 145 MPa in 0.2% offset yield strength for the annealed CG counterpart) and high ductility (~11% in uniform elongation). Our results show that the ultra-fine lamellar structure takes a volume fraction as high as 42.5% and presents a high strength (~450 MPa in 0.2% offset yield strength), enabling it to make a substantial contribution to the high overall strength of the multi-scale alloy. Interestingly, the ultra-fine lamellar structure concurrently exhibits a reasonably high ductility (~6% in uniform elongation), which benefits for the multi-scale alloy to attain the high ductility.