Vickers microhardness and indentation fracture toughness of tantalum sesquinitride, η-Ta2N3. Issue 1 (January 2016)

• Record Type: Journal Article
• Authors: Bourguille, Judith; Brinza, Ovidiu; Zerr, Andreas
• Is Part Of: Ceramics international. Volume 42:Issue 1:Part A(2016)
• Page Start: 982
• Page End: 985
• Publication Date: 2016-01
• Subjects: C. Hardness -- C. Toughness and toughening -- D. Nitrides; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2015.08.130
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Vickers indentation testing was applied to examine an additive-free monolithic sample of tantalum sesquinitride having orthorhombic U2 S3 type structure, η-Ta2 N3, synthesised at high pressures and temperatures. Crystallisation of η-Ta2 N3 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-Ta2 N3 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 Si3 N4 and SiC.