Effect of Tantalum Solid Solution Additions on the Mechanical Behavior of ZrB₂

Abstract

Mechanical properties and microstructure were compared for zirconium diboride and two zirconium diboride solid solutions containing 3 and 6 at% tantalum diboride. X-ray diffraction indicated that the ceramics were nearly phase-pure and that tantalum dissolved into the ZrB2 lattice to form (Zr,Ta)B2 solid solutions. Microstructural analysis indicated that samples achieved nearly full relative density with average grain sizes that ranged from 3-5 μm. The three compositions had similar values of Young's modulus (510-531 GPa), shear modulus (225-228 GPa), Vickers hardness (15.2-16.4 GPa), and flexural strength (391-452 MPa). Fracture toughness ranged from 2.6 to 3.7 MPa m1/2 and with increasing tantalum content, the fracture mode changed from predominantly intergranular to predominantly transgranular. Diboride solid solution materials had comparable properties to the single metal diboride, but differences in microstructure, secondary phases, and strain state among the three ceramics partially obscured the actual effects of the solid solution on fracture behavior.

Department(s)

Materials Science and Engineering

Comments

Honeywell Federal Manufacturing and Technologies, Grant N000335755

Keywords and Phrases

Mechanical Properties; Solid Solutions; Solute Effects; Ultra-High Temperature Ceramics; Zirconium Diboride

International Standard Serial Number (ISSN)

0955-2219; 1873-619X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2021 European Ceramic Society, All rights reserved.

Publication Date

01 Jan 2021

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