Characterization of TiCxN1-x-TiCrNbMoTa composites as refractory hard materials

Abstract

TiCxN1-x-TiCrNbMoTa (X = 0, 0.5, 0.7, 1.0) composites as novel refractory hard materials were fabricated via powder metallurgy processes and their composition, microstructure, and mechanical properties were evaluated. TiCrNbMoTa refractory high entropy alloy (RHEA) synthesized via mechanical alloying of raw metal powders was used as a binder material of the TiCxN1-x hard grains. Microstructure of the TiCxN1-x-TiCrNbMoTa composites was composed of three phases: bcc TiCrNbMoTa phases, TiCXN1-X hard phases and TiCXN1-X-based hard phases including the TiCrNbMoTa contents. The presence of the third phases suggested that a part of the RHEA contents diffused into the TiCXN1-X phases to form some compounds or solid solutions. Changes in mechanical properties of the composites such as hardness and bending stress as a function of temperature were influenced by the ratio of TiN to TiC in TiCxN1-x grains; the higher ratio of TiN was better for the high temperature mechanical properties and oxidation resistance whereas a partly replacement of TiN with TiC was better to improve the mechanical properties of the composites over the wide temperature range (R.T. to 1473 K).