Fabrication and characterization of high-temperature niobium alloy coatings



The alloys based on the combination of refractory metals with elements known for enhancing oxidation resistance, high-temperature strength, and thermal stability are desirable for high-temperature applications. Such alloys find widespread applications in many of the advanced aerospace and energy technologies. Niobium (Nb) is one of those refractory metals with a high potential to design and develop novel alloys for high-temperature applications. Therefore, in the present work, we performed a detailed study on the NbCrTaWV alloy coatings made by magnetron sputtering. The coatings were made under variable deposition temperature. Further characterization and analysis were made using X-ray Diffraction (XRD) and scanning electron microscopy (SEM). The results indicate the structure and morphology variation as a function of deposition temperature. We hypothesize that the composition and/or formation energy of each metal in the alloy would result in texturing and preferential orientations. To validate this hypothesis combined used of XRD and crossectional SEM was performed. Finally, nanoindentation measurements were made to understand the mechanical properties of the Nb-based alloy coatings. The results will be presented and discussed to explain the structure-morphology- mechanical property correlation in Nb-based multicomponent alloy coatings.

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Colin Bill
Very interesting presentation. What was the rationale for using the combination of NbCrTaWV alloys in your experiments?
Sourish Dutta
The main rationale for using the five distinct transition metals is as follows: Tantalum and Tungsten alloys are known to retain a majority of their physical and optical properties even at high temperatures mainly due to their high melting points. Chromium was incorporated to enhance the oxidation resistance property of the alloy at high temperatures and close proximity to O2 combustion. Vanadium is added to improve the thermal stability of the metal at high temperatures and prevent mass diffusion or conglomeration of the atoms at high temperatures as shown through the EDS scans. Finally, the host metal Niobium was used to increase the overall durability and strength of the HEA as supported by previous literature. Since the main purpose of our Nb-based HEA was thermal coatings, we theorized that the distinct properties of each metal could be optimized in this HEA formation for high performance in extreme environments.
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