Feasibility of using Ni25Co20Cu10Fe25Mn20 high entropy alloy as a novel sintering aid in ZrB2 ceramics

Abstract

For the first time, Ni25Co20Cu10Fe25Mn20 high entropy alloy (HEA) was employed as a sintering aid for fabrication of ZrB2-based ceramics using spark plasma sintering (SPS) process. The mechanical properties, phase evolution, microstructural changes, and the densification mechanisms of ZrB2-5 wt% HEA ceramics during the SPS step were scrutinized. The ZrB2-5 wt% HEA ceramic, manufactured at 1900 °C, yielded interesting combination of properties, counting a relative density of 96%, a fracture toughness of 6.4 MPa m1/2, and a hardness of 12.6 GPa. According to XRD patterns, there were ZrC and ZrO2 phases with ZrB2 matrix in the sintered samples. An unknown phase was also observed in the XRD patterns. Based on the history of the NiCoCuFeMn alloy and separation of Cu within the temperature range of 650–850 °C, that phase was related to CuB.