Interfacial reaction in squeeze cast SiC_w/AZ91 composites with different binders

The whisker/matrix interfaces in squeeze cast SiC_w/AZ91 composites with different binders (silica binder, acid aluminum phosphate binder and without binder) were studied by transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). The SiC_w/AZ91 interface is very clean in the composites with no binders. For the composites with acid aluminum phosphate binders or silica binders, there exists fine discrete interfacial reaction products MgO at the interface, and a definite orientation relationship between MgO and SiC_w. The interfacial reaction products MgO is unevenly distributed at different parts of the composite ingot with silica binder, and mainly distributed to the interface at the side part of the composite cylinder. While in the SiC_w/AZ91 composite with acid aluminum phosphate binder, MgO particles are distributed evenly at the interface in almost all the parts of the composite ingot.