Influence of spark plasma sintering and conventional sintering on microstructure and mechanical properties of hypereutectic Al-Si alloy and hypereutectic Al-Si/B4C composites

Al-Si compacts and Al-Si/B4C composites were fabricated by conventional cold pressing + sintering and spark plasma sintering techniques. The effects of powder metallurgy techniques on density, microstructural properties, hardness, and transverse rupture strength were investigated. The advantages of spark plasma sintering, which is one of the fast sintering techniques, over conventional sintering were discussed. Green densities and sintered densities were found to decrease with increasing B4C addition. The relative density values of the samples produced with spark plasma sintering are over 96 %. B4C particles were clustered at the grain boundaries of the master alloy and/or in the intergranular pores. An increase of approximately 40 % was determined in the hardness values of the spark plasma sintering samples compared to the cold pressing+sintering samples. Transverse rupture strength was increased in spark plasma sintering samples containing 5 and 10 wt.% B4C.