Cold Consolidation of Metal–Ceramic Nanocomposite Powders with Large Ceramic Fractions

Co/ α ‐Al 2 O 3 powder mixtures (5, 10, 20, 30, 40, and 50 mass % of α ‐Al 2 O 3 ) have been ball‐milled and, subsequently, consolidated at room temperature by means of a high pressure torsion procedure in order to produce bulk nanostructured composites. For mixtures up to 20% of α ‐Al 2 O 3 , the cold‐compaction results in roughly fully dense disks with relatively high microhardness values. However, the compaction for 30, 40, and 50% of α ‐Al 2 O 3 is less effective, resulting in a reduction of the microhardness although a structure in the nanoscale range is still preserved. A detailed structural investigation has been also performed.