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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. Cu 4 Ti 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 Cu 4 Ti 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.

Wear is the primary cause of the failure of joint replacement prostheses. In this paper, the ultra-high molecular weight polyethylene (UHMWPE) as an artificial joint acetabular material was filled with nano-powder of SiO2 of various mass fractions. The effect of SiO2 mass fraction on the tensile strength, tensile modulus, wetting property and tribological properties of the SiO2-UHMWPE composites were investigated when sliding against Ti-6Al-4V under lubrication of physiological saline water. The morphologies of the worn surfaces of composites were observed with optical microscope. As a result, the tensile strength, tensile modulus, wettability and wear resistance of the composites were all improved by filling with SiO2, and the composites had largely decreased friction coefficients under lubrication of physiological saline water compared with the unfilled UHMWPE. This was attributed to the reinforcing function of the nano-powder of SiO2 in the composites and the lubricating action of the water boundary film. The wear of pure UHMWPE was dominated by plowing, plastic deformation, while the SiO2-UHMWPE was characterized the mild fatigue wear.

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