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

Abstract

The microstructure of β-type SiC whiskers (SiC_w) used in an Al(Li, Cu, Mg, Zr)-SiC_w 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 SiC_w were observed. Four kinds of SiC_w existing in the composite are discussed. Twin boundaries, polytypes and extended dislocations in SiC_w were studied by HRTEM. Dislocation emission from the twin tip and reaction between two extended dislocation indicated that there were some interstitial atoms in SiC_w, 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 SiC_w-Al interface in the composite were also investigated.