Synthesis of an Al/Al2O3 composite by severe plastic deformation

The influence of severe plastic deformation on fabrication of an aluminum/alumina composite made from pre-sintered Al powders was evaluated. Spherical powder particles with diameters up to 45 μm were pre-compacted using cold isostatic pressing (CIP), subsequently vacuum sintered for 60 min at 500 °C, and subjected to processing using either 4 passes of swaging or 1 or 10 revolutions of high pressure torsion (HPT). For all the samples we calculated average strain and measured microhardness. Results showed an increase in microhardness with an increase of the imposed strain. However, the microhardness values and uniformity were also influenced by possible residual porosity. The smallest and most uniform grain size was achieved for the samples processed by HPT, especially after 10 revolutions (average diameter of 0.22 μm). Residual porosity was completely eliminated only after 10 HPT revolutions. Texture evaluations showed 〈111〉 fiber texture development after swaging, while grain orientations after HPT were more random.