Effect of Cu content on microstructures and mechanical properties of Al-Cu-Mg alloy fabricated by large strain rolling

The effects of Cu content on microstructures and mechanical properties of Al-Cu-Mg alloy were investigated by optical microscopy, X-ray diffraction, tensile tester, scanning electron microscope and transmission electron microscope. The results show that there is obvious dendrite segregation in as-cast Al-Cu-Mg alloys, and a large number of massive S(Al2CuMg) and θ(Al2Cu) precipitates are distributed along the grain boundaries. After homogenization annealing treatment, the non-equilibrium low-melting phases are substantially dissolved into the matrix, and the intergranular structure distribution tends to be more uniform. After large strain rolling deformation, typical fibrous structures are obtained in the three kinds of Al-Cu-Mg alloys and the main secondary phases in the alloys are S(Al2CuMg), θ(Al2Cu) and T(Al20Cu2Mn3), which are continuous along the grain boundaries and evenly distributed. After aging treatment, all three kinds of Al-Cu-Mg alloys exhibit excellent comprehensive mechanical properties. When the Cu content is 2%(mass fraction), the tensile strength, yield strength and elongation are 507 MPa, 430 MPa and 10.3%, respectively. With the increase of Cu content, the mechanical properties of Al-Cu-Mg alloys show increasing trends, and the increase of Cu content has a significant effect on the mechanical properties of the alloy. When the Cu content is 4.5%, the tensile strength, yield strength, and the elongation of Al-Cu-Mg alloy are 644 MPa, 547 MPa, and 10.5%, respectively. © 2019, Science Press. All right reserved.