Regulation Mechanism of Novel Thermomechanical Treatment for Microstructure and Properties of 2E12 Aluminum Alloy

The effects of a novel thermo-mechanical treatment (TMT) on the mechanical properties and the microstructure of 2E12 aluminum alloy were investigated by tensile test and fatigue crack propagation test, as well as scanning electron microscope and transmission electron microscope (TEM). Results show that a good combination of strength and plasticity can be achieved for 2E12 aluminum alloy by the new TMT, the yield strength increases by ∼28% over that of T3, and the ultimate tensile strength also increases by 17%, while the high elongation of T3 condition (over 16%) is maintained. The fatigue crack growth rate of the TMT is lower than those of the T3 and T6 peak aged samples. A high density of tangled dislocation is contained in the TMT 2E12 aluminum alloy, and dislocation cell substructure is formed. The mechanism of the new TMT technique, by which the mechanical properties of the alloy is greatly increased, is the synergistic effect of composite structures, including dislocation cell substructures, the complex of Mg/Cu/vacancies, as well as GPB zones.