ROLE OF MG AND TI ON A SICP,ZRCP/AL COMPOSITE AT ELEVATED-TEMPERATURES

Metal-matrix composites have been considered as new materials with many attractive properties. One of the characteristics of particulate composites is high strength at elevated temperatures. In this work, a SiC- or ZrC-particle-reinforced composite was fabricated through a casting route and the effect of Ti and Mg alloying on the wettability between ceramic particles and a liquid aluminium alloy was measured with the time required for particulate incorporation. The formation of a reaction product was observed and it was identified by scanning electron microscopy (SEM) and X-ray microanalysis. Observations by SEM revealed that the incorporation time was closely related to the interfacial reactions. The degradation of the composite at an elevated temperature was measured, and the roles of the interfacial reaction and the formation of the reaction product were investigated. Decomposition of the ceramic phase due to the elevated-temperature holding depended on the thermodynamical properties of the ceramic phase. The formation site of the reaction product also affected the degradation of the composite material.