Abstract: In this work, the microstructures of hotextruded tubes and cuplike parts were observed by SEM and TEM. The Vickershardness and tensile properties were investigated. The results indicate that SiC whiskers tend to break and distribute directionally. The extrusion temperature is an important factor in final microstructure and properties of extruded parts. It is also shown that the unevenly distributed hardness is caused by the uneven flow of metals. An aging treatment of extruded parts will greatly increase the tensile strength.