Diffusion barrier effect of Ta or TaSi2 layer at the MoSi2/Nb-based alloy interface

Fabrication and Oxidation Resistance of a Novel MoSi2-ZrB2-Based Coating on Mo-Based Alloy

“…Applying a diffusion barrier between the MoSi 2 -based coating and the refractory metals substrate is another way to improve the stability and serving life of the coating. Many kinds of materials, including oxides (Al 2 O 3 diffusion barrier for the Mo-Si-B/Nb-Si system [ 33 ], Y 2 O 3 diffusion barrier for the MoSi 2 /Nb-Si system [ 34 ]), carbides (Mo 2 C diffusion barrier for the MoSi 2 /SiC-Mo 2 C/Mo system [ 35 ], SiC-glass diffusion barrier for the MoSi 2 /Nb-Si system [ 36 ]), borides (MoB diffusion barrier for the MoSi 2 /Mo system [ 8 , 37 ], Nb 3 B 2 -NbB 2 diffusion barrier for the Si-Mo-W-ZrB 2 -Y 2 O 3 /Nb system [ 38 ]) and silicides (TaSi 2 diffusion barrier for the MoSi 2 /Nb system [ 39 ], WSi 2 diffusion barrier for the MoSi 2 /Nb-Ti-Si system [ 40 ]) have been used as diffusion barriers between the coatings and the substrates, thereby effectively lengthening the lifetime of these coatings. Reference [ 25 ] demonstrated that the Mo 2 C barrier layer plays a key role in slowing down the diffusion of C and Si toward the inner Mo substrate at high temperatures, which led to less cracks in the surface and a thinner Mo 5 Si 3 layer at high temperatures in air and thus brought about better oxidation resistance.…”