Microstructural, chemical, and mechanical characterization of extruded Al-Cu-Li rods

Abstract

This work investigates the influence of the alloying elements in rods of the alloys Al-Cu-Li produced by novel powder metallurgy routes. In the first route, the powders were mixed and uniaxial cold-pressed, followed by hot extrusion to produce 5 mm diameter rods. The second route introduced an intermediate step of heat treatment that was carried out at 525 °C for 1 h in a pure N2 atmosphere before the extrusion. This was done to evaluate the importance of homogenization of the alloying elements during the heat treatment, as well as the tendency to form new phases in the extruded rods. The obtained rods were characterized by SEM, EBSD, Vickers microhardness, chemical composition (ICP-OES), and tensile tests. The results obtained showed that the alloy 1 (AA2060) presents a more homogeneous microstructure than alloy 2 (AA2196), and it is observed the benefit of Mg addition, which improves the microstructure after HT. The EBSD analysis showed a typical preferential orientation of a duplex fiber texture. The ICP-OES analysis reports losses of Li and Mg for both alloys. Regarding to the measurement of hardness, the results were very different depending on the alloy and the HT prior to the extrusion process.