LAUSR

Abstract Cold-rolled commercial AA2219 and model Al-2 wt%Mn-2 wt%Cu(2Mn2Cu) alloys have been compared in phase composition, microstructure, physical and mechanical properties after different heat treatment routes. The as-cast structure of the model alloy proves to be similar to the homogenized structure of the branded alloy, providing a far shorter technological route required for obtaining a 95% cold reduction ratio. The principal possibility of obtaining cold rolled sheet products with a sufficiently high set of mechanical properties and electrical conductivity without the necessity of homogenization annealing, solution treatment, and water quenching has been shown. Electron microscopy, X-ray diffraction and Thermo-Calc software simulation have been used for optimizing the alloy composition. It has been shown that the as-cast structure of the model alloy has the minimum quantity of Al2Cu eutectic inclusions, and almost all manganese content and about 1.2% Cu are dissolved in the aluminum solid solution. This structure provides for a high plasticity that allows for deformation of ingots without their preliminary homogenization. The formation of the Al20Cu2Mn3 nano-sized dispersoids (with volume fraction of about 7 vol%) has been found to provide for the retaining of the fiber-like (non-recrystallized) grain structure in the model 2Mn2Cu alloy after annealing at 400 °С (3 h), despite a very high cold rolling reduction ratio (95%). The model alloy exhibits a substantially higher strength performance after annealing at 400 °С in comparison with the AA2219 alloy. For example, the YS value of the model alloy is 210 vs 86 MPa. This indicates a higher tolerance of the model alloy toward softening. Summing up the results, the ternary 2Mn2Cu model alloy shows a potential to become the basis for designing new high-tech heat-resistant alloys as a sustainable alternative to 2xxx alloys.