On the Enhancement of the Microstructure and Tensile Properties of an Al–Cu Based Cast Alloy

The present work was carried out on an Al–Cu alloy containing 6.5%Cu, 0.1%Si, 0.4%Mn, and 0.18%Zr (coded HT200). The investigations included hot-tearing tests, microstructural characterization, and tensile properties at room temperature (25 °C). The results were interpreted in terms of application of grain refiner, solidification rate, and phase precipitation. Grain refining using TiBor (0.15%Ti) coupled with high solidification rate (~ 8 °C/s) is proven to be very effective in reducing the alloy hot-tearing sensitivity to be equal to that of A319 alloy with an average grain size of ~ 50–80 µm. In contrast to A319 alloy, the present HT200 alloy required a single step solutionizing treatment (4 h at 520 °C) followed by water quenching to achieve maximum dissolution of the Cu phase. The alloy also exhibited a fast response to aging treatment, resulting in a significant improvement in the alloy tensile strength and quality.