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The present study deals with mechanical properties of the bulk tantalum ceramics at elevated temperatures up to 2000 °C. In situ phase transformation and change in the grain size were observed during high temperature flexural tests performed on tantalum nitride bulks consolidated by spark plasma sintering. This study, for the first time, shows that tantalum nitride with cubic structure is the main phase at temperatures between 25 °C and 2000 °C, while previous studies suggested it should be hexagonal TaN. Cubic TaN phases with lattice parameters of a = 4.338 Å and a = 4.44 Å were observed below 1600 °C and above 1600 °C, respectively. The possibility of the formation of multiple TaN phases during the flexural tests significantly increases the high-temperature strength as values of greater than 500 MPa were observed at 1600 °C. This strength level is typical for the bulk TaC at room temperature. We anticipate that the approach presented in this study would allow to clarify and obtain additional information about transition metal – nitrogen phase diagrams.

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• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  © 2021. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

Keyword: binary phase diagram, flexural strength, toughness, high-temperature materials

Date published: 2021-08-20

Publisher: Elsevier BV

Journal:

• Materials Science and Engineering: A (ISSN: 09215093) vol. 826 141954

Funding:

• National Institute for Materials Science PA5180 (セラミックスプロセッシング)
• National Institute for Materials Science PA3030 (粉体・セラミックス 結晶・界面の階層的構造制御による機能顕在化のための研究)

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4984

First published URL: https://doi.org/10.1016/j.msea.2021.141954

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Updated at: 2024-11-19 16:30:09 +0900

Published on MDR: 2024-11-19 16:30:11 +0900