The Cu matrix cermets remarkably strengthened by TiB2 “in situ” synthesized via self-propagating high temperature synthesis

Abstract

The TiB2–Cu cermets with predominant concentration of superhard TiB2 (from 45 to 90vol.%) were fabricated using elemental powders by means of SHS (self-propagating high-temperature synthesis) process and simultaneously densified by p-HIP (pseudo-isostatic pressing technique). The heat released during highly exothermic SHS reaction was “in situ” utilized for sintering. The combustion occurred even for 50vol.% Cu dilution. According to XRD metallic copper binder was formed in those cermets in whole range of investigated compositions. The TiB2 volume fraction significantly influenced the properties of fabricated materials, especially grain size and hardness. Both the average grain size and hardness significantly increased with TiB2 content, so the maximum value of 18GPa was measured for TiB2–5vol.%Cu composite. Coarse grains of 6.4μm in size were observed for this composite while TiB2-based submicro-composites were formed for 40–50% of Cu where the average grain size did not exceed 0.6μm. The Vickers hardness of 16–18GPa obtained for cermets containing from 85 to 90vol.% of TiB2 and no radial cracks in Vickers hardness test proved that in term of hardness and fracture toughness the composites might be competitive to WC–Co cermets.