Formation and oxidation behavior of refractory high-entropy silicide (NbMoTaW)Si2 coating

A single high-entropy silicide (NbMoTaW)Si2 coating was prepared on NbMoTaW refractory alloy by a halide activated pack cementation process. The formation mechanism and growth kinetics of the (NbMoTaW)Si-2 coatings were analysed. The oxidation behavior of the (NbMoTaW)Si-2 coatings was investigated at 1300 degrees C for 24 h in air. The results showed that the high entropy effect and sluggish effect of the high-entropy NbMoTaW alloy makes it form a single-phase silicide (NbMoTaW)Si-2 during the Si diffusion growth process. The lattice distortion effect of substrate provides a channel for the diffusion of Si to accelerate its diffusion rate. The (NbMoTaW)Si-2 coating effectively protects the NbMoTaW alloy from oxidation at 1300 degrees C . The oxidation resistance of the coating is attributed to the preferential oxidation of Si to produce a dense continuous SiO2 scale and the precipitation of WSi2 to suppress the interdiffusion of the silicide layer and the alloy substrate.

Automated summary

A high-entropy silicide coating was successfully prepared on NbMoTaW refractory alloy using a halide activated pack cementation process. The coating demonstrated excellent oxidation resistance at high temperatures due to the selective oxidation of Si and the precipitation of WSi2.