Superfast preparation of Al-Sc alloys with high Sc content by spark plasma sintering

Aluminum-scandium alloys with high scandium content by mass were prepared by spark plasma sintering (SPS). The morphology, the phase composition, and the microstructures after sintering at different temperatures of Al-Sc alloy powders were investigated by scanning electron microscope (SEM), energy dispersive spectrometry (EDS), and X-ray diffractometry (XRD). The effect of sintering temperature on the microstructure of Al-Sc alloys was studied in the paper. The results show that, the Al-Sc alloy powders after ball milling are regular with the particle size of 25~45 μm, and the mechanical alloying of Al-Sc alloy powders is realized initially. In addition to the Al and Sc phases, a small amount of Al₃Sc and AlSc₂ are generated. The spark plasma sintering can realize the rapid densification of Al-Sc alloy with high scandium content, the Al-Sc alloy with 30% Sc by mass is successfully produced by SPS method. By adjusting the SPS process parameters, the relative density of sintered sample can be improved to 92.19%. The samples with the higher density and non-obvious grain boundary are achieved at the sintered temperature above 500℃. The second phases of Al₃Sc and AlSc₂ are formed by the combination of Sc with the increase of sintering temperature, and the peak intensity of Al₃Sc increases gradually.