Microstructure and Friction Properties of TiB₂@Ti/CoCrFeNi High Entropy Alloy Matrix Composite

TiB₂@Ti/CoCrFeNi high-entropy alloy matrix composite (HEAMC) powders and bulk materials were prepared by mechanical alloying and spark plasma sintering. The microstructure of the powders was characterized, and the microstructure, hardness, and friction properties of the bulk materials were investigated. Results showed that after low-energy ball milling for 8 h, the composite powder presented an ellipsoidal or granular shape with an average particle size of approximately 80 µm. The phase structure was mainly composed of FCC, Ti, and TiB₂ phases. The phase structure of the sintered composite was mainly composed of FCC and a small amount of TiB₂ phases. The microhardness of the composite was 362 HV, which was approximately 188 HV higher than that of the matrix alloy. The average friction coefficient was approximately 0.6664, which was 0.087 lower than that of the matrix alloy. The improvement in the hardness and friction performance of the composite was mainly attributed to the strengthening of grain boundary caused by the enrichment of TiB₂ particles and Cr₂O₃ along the grain boundary and the solid solution strengthening of Ti. The wear types were mainly abrasive and oxidative wear for the composite and CoCrFeNi matrix alloy.