INFLUENCE OF MICROSTRUCTURES AND PARTICLE CONCENTRATIONS ON THE DEVELOPMENT OF EXTRUSION TEXTURES IN METAL-MATRIX COMPOSITES

Crystallographic textures and microstructures induced by extrusion in aluminium alloys reinforced by silicon carbides are analysed in some d etail. It is shown that the crystallographic texture and the morpholog y of the Al phase vary with the SiC percentage and distribution. When the SIC concentration is low (i.e. less than 10%), the particles are d ispersed randomly within the matrix and the texture intensity is great er than that of the Al alloy deformed under the same conditions. For h igh concentrations (i.e. greater than 10%) the particle distribution i s no longer uniform and the Al texture tends towards isotropy. Simulta neously, the Al grains, which are very elongated in the particle-free alloy, break into subgrains during deformation in the composite materi als. To interpret these various observations, extrusion textures have been simulated with a viscoplastic self-consistent model, introducing several concentrations of SiC and the specific morphology of the compo site material. The experimental trends can thus be quantitatively repr oduced and explained. the influence of the Al morphology and the parti cle distribution on the Al texture is clearly shown.