Micro-pore formation and mechanical properties in a hyper-eutectic Al-Si alloy fabricated by spark plasma sintering

The samples were fabricated with various conditions in spark plasma sintering (SPS) by using a rapidly solidified powder of a hypereutectic Al-16%Si alloy. Micro-pores and Si particles were investigated metallographically, and density and Vickers hardness were estimated. As a result, micro-pores were randomly distributed in the sample preheated under a pressure before SPS but they were distributed like network along powder particles after a higher electric current application of SPS. The density decreased as electric current of SPS increased. The size and volume fraction of Si particle increased, while Vickers hardness decreased as the electric current of SPS increased. A part of the decrease in hardness is considered to be caused by particle dispersion hardening mechanism