Transmission electron microscopy study on microstructures of an Al(Li, Cu, Mg, Zr)-SiCwcomposite

Abstract
The microstructure of β-type SiC whiskers (SiCw) used in an Al(Li, Cu, Mg, Zr)-SiCw composite has been investigated by means of transmission electron microscopy (TEM), mostly by using high-resolution TEM (HRTEM). Three configurations of transition areas at knots in SiCw were observed. Four kinds of SiCw existing in the composite are discussed. Twin boundaries, polytypes and extended dislocations in SiCw were studied by HRTEM. Dislocation emission from the twin tip and reaction between two extended dislocation indicated that there were some interstitial atoms in SiCw, which might be introduced by heat pressing and extruding during the manufacture of the composite. The related phases of δ′, S′, β′ and MgO at or adjacent to the SiCw-Al interface in the composite were also investigated.