Spark plasma sintering of an Al-based powder blend

The present study investigates the sintering response of a hypereutectic aluminum–silicon alloy, specifically Alumix-231 (Al–14Si–2.5Cu–0.5Mg), using Spark Plasma Sintering (SPS). The focus was to link the influence of the sintering parameters to the sintered density, microstructure, hardness and flexural properties in T1 and T6 conditions. The results were compared to those obtained using the conventional press and sinter route, a method typically used for this alloy. The samples consolidated using SPS attained densities between 95% and 100%TD compared to those obtained by conventional sintering which were approximately 94%TD. Before and after the aging heat treatment, microhardness and mechanical properties were assessed for both SPS and press-sinter samples. After sintering, in the T1 condition, a hardness of 89±7 HV, a flexural strength of 702±28 MPa and a flexural strain of 6.2±1.2% were obtained for the SPS samples. In the T6 condition, a hardness of 157±5 HV, a flexural strength of 654±38 MPa and a flexural strain of 4.4±0.2% were obtained in the ideal SPS conditions. On the other hand, a hardness of 137±8 HV, a flexural strength of 315±69 MPa, and a flexural strain of 3.4±0.1% were achieved for the conventional sintering process after the T6 heat treatment. The hardness in the T1 condition was lower than what had been reported in the literature, however after a T6 heat treatment, hardness values obtained in this study were similar to previous work. On the other hand, the difference in flexural properties was unlike previous studies.