Fabrication of TiC-CoCrFeMoNi composites through various powder processes

Abstract

TiC-CoCrFeMoNi composites were fabricated via different powder metallurgy processes and their microstructures and mechanical properties were evaluated from room temperature to high temperatures up to 1273 K. One of the composites was prepared via the arc melting of raw metal powders and another was prepared via the mechanical alloying of the raw powders for the formation of a high-entropy alloy (HEA) of CoCrFeMoNi. The third composite was prepared via a reaction sintering process to form an HEA from raw metal powders. The obtained TiC-CoCrFeMoNi samples were composed of TiC phases, Mo-containing TiC phases, and HEA phases, and the microstructure varied among the three samples. The HEA phase was composed of a single fcc phase and the concentration of Mo in the HEA phases was low for all the three samples because most of the Mo atoms diffused from the HEA into the TiC hard phases. The Vickers hardness at 1273 K ranged from 62% to 64% of that at room temperature for the three samples. The bending stress started to decrease at 1173 K with increasing temperature, irrespective of the fabrication process. Thus, a low concentration of Mo in the HEA phase or a high solid solution of Mo in the TiC phase can improve the hardness and bending stress at high temperatures.