In Situ Transmission Electron Microscopy for Ultrahigh Temperature Mechanical Testing of ZrO<sub>2</sub>.

Grosso, Robson L; Muccillo, Eliana N S; Muche, Dereck N F; Jawaharram, Gowtham S; Barr, Christopher M; Monterrosa, Anthony M; Castro, Ricardo H R; Hattar, Khalid et al. · Nano Lett · 2020

biomechanical · Level V

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Abstract

This work demonstrates a novel approach to ultrahigh-temperature mechanical testing using a combination of in situ nanomechanical testing and localized laser heating. The methodology is applied to characterizing and testing initially nanograined 10 mol % Sc<sub>2</sub>O<sub>3</sub>-stabilized ZrO<sub>2</sub> up to its melting temperature. The results suggest that the low-temperature strength of nanograined, <i>d</i> < 50 nm, oxides is not influenced by creep. Tensile fracture of ZrO<sub>2</sub> bicrystals produce a weak-temperature dependence suggesting that grain boundary energy dominates brittle fracture of grain boundaries even at high homologous temperatures; for example, <i>T</i> = 2050 °C or <i>T</i> ≈ 77% <i>T</i><sub>melt</sub>. The maximum temperature for mechanical testing in this work is primarily limited by the instability of the sample, due to evaporation or melting, enabling a host of new opportunities for testing materials in the ultrahigh-temperature regime.