Metallic glasses (non-crystalline alloys) are of interest for their exceptional (sometimes record-breaking) property combinations, for example, high yield stress combined with high toughness. Yet as the glasses relax (‘age’) into lower-energy states, they become more brittle. There is much interest, therefore, in taking the glasses in the opposite direction, to higher-energy ‘rejuvenated’ states. One method would be to form the glass at a higher quenching rate, but that is achievable only for ultra-thin sections.
This work shows that, by compression in a constrained geometry, a bulk sample of a metallic glass can be taken to a highly rejuvenated state that would be typical of a glass formed on cooling at 1010 K s–1, 7 to 8 orders of magnitude higher than the cooling rate at which the sample actually formed.
Figure: Map of hardness measured on the cross-section of a notched cylindrical (4 mm diam.) sample of metallic glass compressed along the vertical cylinder axis. The yellow region and those within are rejuvenated; the blue colour indicates the regions of extreme softening and rejuvenation.
J. Pan, Y.X. Wang, Q. Guo, D. Zhang, A.L. Greer, Y. Li, "Extreme rejuvenation and softening in a bulk metallic glass", Nature Communications (2018)