19 October 2024: New publication in Acta Materialia

In this article, we report an in situ TEM investigation of the mechanical properties of amorphous olivine (a-olivine) in tension using a Push-to-Pull (PTP) device. We find that at small scale a-olivine is ductile, reaching a fracture strain close to 30 % with a strength up to 2.5 GPa.

We observe a strong sensitivity to electron irradiation, with, under electron illumination at 200 kV, a strength which is lower, around 1.7 GPa, and higher elongations close to 36 %. Alternating beam-off and beam-on sequences lead to exceptionally large fracture strains equal to 68 % at 200 kV and 139 % at 80 kV. The strain-rate sensitivity is 6 to 10 times higher when a-olivine is deformed under electron irradiation. EELS measurements show that radiolysis (inelastic electron-electron interactions) is responsible for this behavior.

In this study, 1D model is presented to analyze the complex aspect of the mechanical data under alternating beam off and beam on. Modeling the load transfer between the PTP device and the specimen is necessary to interpret the data at this scale.

To learn more:

A. Orekhov, G. Kermouche, A. Gomez-Perez, P. Baral, R. Dohmen, M. Coulombier, J. Verbeeck, T. Pardoen, D. Schryvers, J. Lin, P. Cordier & H. Idrissi (2024) Room temperature electron beam sensitive viscoplastic response of ultra-ductile amorphous olivine films. Acta Materialia, 282, 120479. https://doi.org/10.1016/j.actamat.2024.120479