Publication Date

6-24-2021

Department

Ames Laboratory; Materials Science and Engineering

Campus Units

Ames Laboratory, Materials Science and Engineering

OSTI ID+

1798863

Report Number

IS-J 10523

DOI

10.1016/j.actamat.2021.117114

Journal Title

Acta Materialia

Volume Number

215

First Page

117114

Abstract

Refractory-metal-based alloys are a potential replacement of current nickel-based superalloys due to their excellent mechanical strength at extremely high temperatures. However, severe oxidation in a high-temperature working environment limits their application. To address this challenge, a two-step coating process (including a Mo precoat and a Si-B pack cementation) was applied to an innovative refractory multi-principal element alloy (RMPEA) (Mo95W5)85Ta10(TiZr)5. The coating is composed of an aluminoborosilica glass layer on top of a RMPEA-Si-B multilayered structure. The coating effectively protects the RMPEA from oxidation in high-temperature environments, as demonstrated by phase-stable operation at 10–20% higher temperatures over state-of-the-art systems without any forced-cooling system. Following an isothermal exposure at 1300 °C, the weight change of the coated sample follows a paralinear kinetics with a minor weight loss of 4.2 mg/cm2 after 50 h. Thermal cycling tests between 1300 °C and room temperature in air resulted in the total weight gain of only 2.6 mg/cm2 after 450 cycles. The coating shows an excellent adherence to the substrate with a boride layer acting as a barrier that maintains the coating integrity. This two-step Mo-Si-B coating method can be adapted to provide environmental resistance to a wide range of RMPEA.

DOE Contract Number(s)

AC02-07CH11358; WBS 2.1.0.19

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Available for download on Friday, June 24, 2022

Included in

Metallurgy Commons

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