Microstructural changes in Al-Cu-Mn alloy reinforced with SiC particles onholding at high temperatures

The microstructural changes were investigated in an Al-Cu-Mn alloy reinforc ed with SiC particles after being kept in the liquid or semi-solid state. T he microstructural and compositional changes were characterized by differen tial thermal analysis (DTA), X-ray diffraction, and scanning electron micro scopy (SEM) equipped with an energy dispersive X-ray analysis (EDXA) system . The solidification behavior of the monolithic alloy is followed by the Al -Cu-Mn ternary system while its composites showed the Al-Cu-Mn-Si quaternar y system due to the rejection of Si from SiC particles after being kept in the liquid or semi-solid state. SiC particles were attacked heavily and a l arge amount of reaction product, Al4C3 was formed. The extent of reaction w as calculated from the contents of Si in matrix by the DTA method for deter mining the liquidus. The result was compared with the quantitative metallog raphy.