High entropy alloy FeCoNiCu matrix composites reinforced with in-situ TiC particles and graphite whiskers

Abstract

FeCoNiCu high entropy alloy matrix composites reinforced by in-situ TiC particles and graphite whiskers (5 vol% and 10 vol%, respectively), i.e., (TiCp + Cw)/FeCoNiCu composites, were fabricated from FeCoNiCuTiC powder system using vacuum inductive melting method. The reaction mechanism of the mixed powder (Fe, Ti and C) and the mechanical properties of resulting (TiCp + Cw)/FeCoNiCu composites were studied. It was found that two reactions (Fe+Ti→FeTiandTi+C→TiC) occurred, when the powder system was heated to 1473 K. The apparent activation energy for these two reactions were calculated and found to be 25 kJ/mol and 2709 kJ/mol, respectively. The TiC particles (size, 3–5 μm) and graphite whiskers (diameter, 0.5–3 μm; length, 10–200 μm) were found to distribute uniformly throughout the high entropy alloy matrix. The crystal structure of FeCoNiCu matrix was FCC type. At room temperature, the maximum tensile strength of the composites was determined to be 566 MPa, representing a 57.7% increase over FeCoNiCu high entropy alloy matrix. Moreover, the elongation to failure of the new composites was determined to be 4.5%. The tensile fracture surface consisted of many fine dimples, suggesting a ductile nature in failure.