In situ TiC/FeCrNiCu high-entropy alloy matrix composites: reaction mechanism, microstructure and mechanical properties

Abstract

In situ TiC particles-reinforced FeCrNiCu high-entropy alloy matrix composites were prepared by vacuum induction melting method. The reaction mechanisms of the mixed powder (Ti, Cu and C) were analyzed, and the mechanical properties of resultant composites were determined. Cu₄Ti were formed in the reaction of Cu and Ti when the temperature rose to 1160 K. With the temperature further increased to 1182 K, newly formed Cu₄Ti reacted with C to give rise to TiC particles as reinforcement agents. The apparent activation energy for these two reactions was calculated to be 578.7 kJ/mol and 1443.2 kJ/mol, respectively. The hardness, tensile yield strength and ultimate tensile strength of the 15 vol% TiC/FeCrNiCu composite are 797.3 HV, 605.1 MPa and 769.2 MPa, respectively, representing an increase by 126.9%, 65.9% and 36.0% as compared to the FeCrNiCu high-entropy base alloy at room temperature. However, the elongation-to-failure is reduced from 21.5 to 6.1% with the formation of TiC particles. It was revealed that Orowan mechanism, dislocation strengthening and load-bearing effect are key factors responsible for a marked increase in the hardness and strength of the high-entropy alloy matrix composites.