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arXiv · 2211.08492

Shear-band cavitation determines the shape of the stress-strain curve of metallic glasses

A. Das·C. Ott·D. Pechimuthu·R. Moosavi·M. Stoica·P. M. Derlet·R. Maass
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Abstract

Metallic glasses are known to have a remarkably robust yield strength, admitting Weibull moduli as high as for crystalline engineering alloys. However, their post-yielding behavior is strongly varying, with large scatter in both flow stress levels and strains at failure. Using x-ray tomography we reveal for the first time how a strain-dependent internal evolution of shear-band cavities underlies this unpredictable post yielding response. We demonstrate how macroscopic strain-softening coincides with the first detection of internal shear-band cavitation. Cavity growth during plastic flow is found to follow a power-law, which yields a fractal dimension and a roughness exponent in excellent agreement with self-similar surface properties obtained after fracture. These findings demonstrate how internal micro-cracking coexists with shear-band plasticity along the plastic part of a stress-strain curve, rationalizing the large variability of plastic flow behavior seen for metallic glasses.

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A. Das, C. Ott, D. Pechimuthu, R. Moosavi, M. Stoica, P. M. Derlet, R. Maass. 2022-11-15. Shear-band cavitation determines the shape of the stress-strain curve of metallic glasses. https://arxiv.org/abs/2211.08492

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