CONSOLIDATION OF NANOMETER-SIZED POWDERS USING SEVERE PLASTIC TORSIONAL STRAINING

Severe Plastic Deformation (SPD) via torsional straining was used to c onsolidate nanometer-sized metallic powders and metal-ceramic nanocomp osites at room temperature. Materials processed using this technique i ncluded copper, Al and nanocomposites based on these metallic nanopowd ers and SiO2, SiC and Al2O3 nanopowders. The as-processed materials we re nearly fully dense. Transmission electron microscopy (TEM) and micr ohardness measurements were used to characterize the materials. The as -consolidated materials had a grain size smaller than the average part icle size of starting powder, indicating grain refinement during sever e plastic torsional straining. Due to the oxidation of the initial nan ometer sized powders, the as-processed samples were very brittle. Ther mal stability was investigated by annealing the as-consolidated sample s at various temperatures and then measuring their microhardness. (C) 1998 Acta Metallurgica Inc.