Vickers microhardness and indentation fracture toughness of tantalum sesquinitride, η-Ta₂N₃

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• 作者：Judith Bourguille ; Ovidiu Brinza ; Andreas Zerr ; ^{zerr@univ-paris13.fr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：C. Hardness ; C. Toughness and toughening ; D. Nitrides
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：42
• 期：1
• 页码：982-985
• 全文大小：672 K

文摘

Vickers indentation testing was applied to examine an additive-free monolithic sample of tantalum sesquinitride having orthorhombic U₂S₃ type structure, η-Ta₂N₃, synthesised at high pressures and temperatures. Crystallisation of η-Ta₂N₃ in form of elongated crystals and a high bulk to shear modulus ratio of 2.3–2.6, considered as a qualitative criterion of malleability, suggest elevated fracture toughness for this ceramic material. Here we measured Vickers hardness, H_V, indentation size effect, and fracture toughness, K_Ic-if, as well as their dependences on the surface self-healing (densification) due to mechanical polishing for a sample with the residual porosity of p=0.14. H_V of η-Ta₂N₃ was found to exhibit a moderate indentation size effect and approach, for the porous sample, H_V(1)=16(1) GPa at the maximal load. K_Ic-if was measured to be 4.6(2) MPa m^1/2, comparable with the values reported for hexagonal Si₃N₄ and SiC.