Processing, microstructure and high temperature dry sliding wear of a Cr-Fe-Hf-Mn-Ti-Ta-V high-entropy alloy based composite

High-entropy materials are promising for high-temperature applications. In order to achieve high-temperature wear resistance, a novel high-entropy alloy based composite, (CrMnFeHf)(7.14)(TiTaV)(23.81), was designed and consolidated by spark plasma sintering at 1320 degrees C following thermodynamic simulations using the CALPHAD method. The microstructure of the sintered composite revealed a Ti30V36Ta19Cr5Mn5Fe4Hf1 body-centered cubic (bcc) high-entropy alloy matrix with C-14 Laves phase and carbide particles. The Laves phase and carbide particles of higher hardness were formed in situ during the sintering in a bcc matrix. The dry sliding wear behavior of the composite against Si3N4 ceramic counter ball (10 N, 30 min) from room temperature to 600 degrees C was investigated. The high-entropy alloy composite showed a superior resistance to wear against Si3N4 ceramic due to the presence of reinforcing C14 laves phase and carbide particles in the high-entropy alloy matrix. Furthermore, the wear rate reduced with increasing temperature. The dominating wear mechanisms of the high-entropy alloy composite were adhesive wear and abrasive wear at room temperature and 200 degrees C, oxidation wear and abrasive wear at 400 degrees C and oxidation wear and delamination wear at 600 degrees C. The formation of multiple oxides, presence of Laves and carbide phase contributed to the low volume loss of high-entropy alloy composite during wear tests at high temperatures.