Microstructure and property of SiC ceramic joints brazed by CoFeCrNiCuTi2 high-entropy alloy with assistance of electric field

Abstract

With the current-assisted bonding technology, the rapid brazing of SiC ceramics was realized at 1125℃ with CoFeCrNiCuTi2 high-entropy alloy as the bonding layer material, which improves the bonding efficiency and ensures the full diffusion of elements. The influence of brazing temperature on the microstructure and mechanical properties of the bonding interface was studied. The results show that the obtained brazed joint has no obvious defects and the weld microstructure is mainly composed of high-entropy FCC, TiC phase and Cr23C6 phase. The formation of TiC reaction layer with dense interface inhibits the decomposition of high-entropy alloy and the formation of intermetallic compounds to a certain extent, and relieves the thermal stress between interface matrix SiC and high-entropy alloy filler. At the same time, due to the delayed diffusion effect of high-entropy alloy filler, the filler in the center of weld still keeps the FCC structure of high-entropy alloy. The mechanical test shows that the strength of brazed joint decreases at first and then increases. When the joining temperature is 1125℃, the maximum bending strength of SiC joint is 37 MPa, which is higher than that of ordinary Ni-based filler by about 21.3 MPa.

Keywords

• brazing
• sic
• high-entropy alloy
• joining
• electric current-assisted sintering technology