Nanoindentation applied on a tungsten - copper composite before and after high-pressure torsion

Abstract Nanoindentation experiments were performed before and after severe plastic deformation of W–Cu composites at room temperature, 200, and 400 °C. The strains were induced by high-pressure torsion (HPT). For the highest degrees of deformation, a particle size of 10 – 20 nanometer was achieved. The nanohardness of copper increased remarkably with increasing deformation, the hardness of tungsten was enhanced only slightly. A temperature of 400 °C during HPT significantly lowered the Cu hardness, probably recrystallisation during HPT had taken place, the hardness of tungsten, however, kept unaffected. With decreasing particle size, the influence of the adjacent material on the measured properties increased as well as the scatter of hardness and modulus. Proceeding to verq small particle and grain sizes, the particles became smaller than the size of the indent. Thus, hardness and modulus values reflected some average over that of pure tungstef and copper.