X-ray Thermo-Diffraction Study of the Aluminum-Based Multicomponent Alloy Al 58 Zn 28 Si 8 Mg 6 .

Newly designed multicomponent light alloys are giving rise to non-conventional microstructures that need to be thoroughly studied before determining their potential applications. In this study, the novel Al 58 Zn 28 Si 8 Mg 6 alloy, previously studied with CALPHAD methods, was cast and heat-treated under several conditions. An analysis of the phase evolution was carried out with in situ X-ray diffraction supported by differential scanning calorimetry and electron microscopy. A total of eight phases were identified in the alloy in the temperature range from 30 to 380 °C: α-Al, α'-Al, Zn, Si, Mg 2 Si, MgZn 2 , Mg 2 Zn 11 , and SrZn 13 . Several thermal transitions below 360 °C were determined, and the natural precipitation of the Zn phase was confirmed after nine months. The study showed that the thermal history can strongly affect the presence of the MgZn 2 and Mg 2 Zn 11 phases. The combination of X-ray thermo-diffraction with CALPHAD methods, differential scanning calorimetry, and electron microscopy offered us a satisfactory understanding of the alloy behavior at different temperatures.