MECHANICAL-PROPERTIES OF AL-SIC COMPOSITES MADE BY RESISTANCE SINTERING OF MECHANICALLY ALLOYED POWDERS

This work has demonstrated the potential of making high strength Al-SiC composites with reasonable ductility by resistance sintering of mechanically alloyed powders. The effects of SiC particle size and content on the mechanical properties of SiC-particulate-reinforced aluminium composites were systematically studied by the use of compressive tests. It was found that the compressive yield stress and ultimate strength increases with increasing SiC volume fraction and decreasing SiC particle size, while the compressive failure strain shows the reverse trend with the variation in SiC particle size and content. The high strength of the resistance-sintered Al-SiC composites may be attributed to the fine subgrain structure in the aluminium matrix, the dislocations generated by differential contraction of aluminium and SiC particulates, and the previous worked structure in the aluminium matrix resulted from the mechanical alloying process. In addition, it was suggested that, besides the formation of liquid phase, the plastic deformation of Al-SiC composite powders also makes a contribution to the densification process in resistance sintering.