Sol-gel alumina coatings for whisker reinforced metal matrix composites

There exist serious interfacial reactions in squeeze-casting aluminum berat e whisker reinforced 6061Al composites. To control the spinel reactions a s ol-gel coating method was used to deposit gamma-Al2O3 and alpha-Al2O3 ceram ic coatings on aluminum berate whiskers. TEM observations of coating morpho logy indicate that nanostructured alumina coatings are uniformly deposited on whisker surfaces, with a thickness of about 30-50 nm. Ball-milling has a n important effect on final mechanical properties of the composites. gamma- Al2O3 and alpha-Al2O3 coatings were found to be effective in controlling th e interfacial reactions, by completely preventing the diffusion of magnesiu m from matrix/coating interface to coating/whisker interface. (C) 2000 Else vier Science S.A. All rights reserved.