Large creep formability and strength-ductility synergy enabled by engineering dislocations in aluminum alloys

Light-weight aluminum alloys are key structural materials widely used in transportation and constructions. Higher strength aluminum alloys are still urgently needed to further improve safety and energy efficiency. However, strength increase usually leads to higher difficulty of manufacturing and ductility loss of the final product. Also, most metallurgical methods to make stronger aluminum alloys are costly and hard to achieve large-scale production. Here, we develop a strategy to dramatically enhance the uniform creep formability of a representative aluminum alloy with an increase of yield strength by 100-200 MPa without compromising ductility compared to that under conventional treatments. The creep strain under an applied stress of 150 MPa is 8 times and 20 times higher than that of conventional T3 and T4 alloy, respectively. The enhanced creep formability and post-form mechanical properties are enabled by engineering dislocations, i.e., tailoring the density and mobility of dislocations in the aluminum alloys upon cold-rolling and creep age forming. The strategy is realized here by bulk metallurgical processes at very low cost. Our effort thus paves a new way for economical manufacturing of stronger aluminum alloy components and sheds light on the enormous untapped potential of the strategy of engineering dislocations.