Metal

Engineering

High entropy alloys

Metallurgy

Materials science

Coating

Layer (electronics)

Silicon

Chemical engineering

Refractory metals

Cementation (geology)

Alloy

Silicide

Cement

Composite material

Journal of Alloys and Compounds

A novel high entropy silicide (NbMoTaWV)Si2 coating was prepared on a NbMoTaWV high entropy alloy by silicon pack cementation. The single-phase structure of (NbMoTaWV)Si2 was obtained due to the high entropy effect and sluggish effect of NbMoTaWV refractory high entropy alloy. The processing parameters could affect the coating structure and thickness. Low temperature favored the formation of single-layer (NbMoTaWV)Si2 layer while high temperatures (1200 ℃ and 1300 ℃) produced two layers coating, (NbMoTaWV)Si2 layer and (NbMoTaWV)Si2/(NbMoTaWV)5Si3 mixed interdiffusion layer. Coating with reasonable thickness and minimized cracks could be obtained under proper processing parameters. The oxidation test of coating specimens was conducted at 1200 ℃ for up to 96 h. The high entropy of (NbMoTaWV)Si2 suppressed the generation of metallic oxides and promoted the formation of dense and intact SiO2 layer, which largely improved the oxidation resistance of NbMoTaWV. Failure in corners was observed in most coating specimens after exposed for 48 h, and the failure mechanism was also discussed.

Development and oxidation behavior of high entropy silicide (NbMoTaWV)Si2 coatings on NbMoTaWV alloy