Microstructure and wear characteristics of Al-Si alloys reinforced with SiC particles

A356 (aluminium hypoeutectic alloy) and Al-18Si hypereutectic alloy have be en selected as matrix (mother) materials. SiC particles were introduced int o the bulk of the A356 alloy with volume fractions (V-f) 10 and 20 %. A sur face layer of SiC-saturated hypereutectic alloy has been produced. Both typ es of composites were produced using the squeeze-casting technique. The mic rostructure of the Al-18Si/metal matrix composite (MMC) layer revealed the refinement of the primary Si crystals in the neighbourhood of the SIC parti cles and their uniform distribution throughout the matrix. This phenomenon is attributed to the high V-f of the SIC particles in the MMC layer, which act as preferable nucleation sites for the primary Si. The wear characteris tics of the A356 composites were superior to those of the conventionally an d squeeze-cast alloys. Among hypoeutectic composites, the A356 + 20 %SiC ex hibited the highest wear resistance. The Al-18Si/MMC layer showed the best wear resistance among all investigated materials. The development of Al-18S i/MMC layer samples can be exploited in new applications for a low-density material with superior surface wear resistance possessing relatively tough core.