Mechanical Properties and Grain Orientation Evolution of Zirconium Diboride-Zirconium Carbide Ceramics

Abstract

The effect of ZrC on the mechanical response of ZrB2 ceramics has been evaluated from room temperature to 2000 °C. Zirconium diboride ceramics containing 10 vol% ZrC had higher strengths at all temperatures compared to previous reports for nominally pure ZrB2. The addition of ZrC also increased fracture toughness from ~3.5MPa√m for nominally pure ZrB2 to ~4.3MPa√m due to residual thermal stresses. The toughness was comparable with ZrB2 up to 1600 °C, but increased to 4.6MPa√m at 1800 °C and 2000 °C. The increased toughness above 1600 °C was attributed to plasticity in the ZrC at elevated temperatures. Electron back-scattered diffraction analysis showed strong orientation of the ZrC grains along the [001] direction in the tensile region of specimens tested at 2000 °C, a phenomenon that has not been observed previously for fast fracture (crosshead displacement rate = 4.0 mm min-1) in four point bending. It is believed that microstructural changes and plasticity at elevated temperature were the mechanisms behind the ultrafast reorientation of ZrC.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Borides; Electron Backscattering Diffraction (EBSD); High-Temperature Mechanical Properties; Particulate Reinforced Composites; Ultra-High Temperature Ceramics (UHTC)

International Standard Serial Number (ISSN)

0955-2219

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 Elsevier Ltd, All rights reserved.

Publication Date

01 Feb 2018

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