Study on the diffusion barrier effect of WSi₂ layer at the MoSi₂/Nb-Ti-Si based alloy interface

WSi₂ layer was introduced at MoSi₂/Nb-Ti-Si based alloy interface to suppress the elemental diffusion. During coating formation process, inward diffusion of [Si] could be retarded and the growth rate of inner NbSi₂ layer was slowed down consequently. At 1250 °C, the MoSi₂/WSi₂ compound coating showed superior oxidation resistance relative to MoSi₂/NbSi₂ compound coating in terms of thinner scale and less MoSi₂ consumption. Parabolic rate constants of scales grew on these two coatings are 0.929 μm² h⁻¹ and 4.782 μm² h^-1, respectively. The improvement was resulted from the WSi₂ layer, which acted as both a diffusion barrier and Si reservoir simultaneously.