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

A novel high entropy silicide (NbMoTaWV)Si-2 coating was prepared on a NbMoTaWV high entropy alloy by silicon pack cementation. The single-phase structure of (NbMoTaWV)Si-2 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)Si-2 layer while high temperatures (1200 ? and 1300 ?) produced two layers coating, (NbMoTaWV)Si-2 layer and (NbMoTaWV)Si-2/(NbMoTaWV)(5)Si-3 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) Si-2 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. (C) 2022 Published by Elsevier B.V.

Automated summary

A novel high entropy silicide (NbMoTaWV)Si-2 coating was prepared on a NbMoTaWV high entropy alloy by silicon pack cementation. The coating exhibited a single-phase or dual-phase structure depending on the processing parameters. The coating showed improved oxidation resistance at high temperatures but was prone to failure at corners.