Enhancing ductility in bulk metallic glasses by straining during cooling
Rodrigo Miguel Ojeda Mota, Ethen Lund, Sungwoo Sohn, David J. Browne, Douglas C. Hofmann, Stefano Curtarolo, Axel van de Walle, Jan Schroers
Abstract
Abstract Most of the known bulk metallic glasses lack sufficient ductility or toughness when fabricated under conditions resulting in bulk glass formation. To address this major shortcoming, processing techniques to improve ductility that mechanically affect the glass have been developed, however it remains unclear for which metallic glass formers they work and by how much. Instead of manipulating the glass state, we show here that an applied strain rate can excite the liquid, and simultaneous cooling results in freezing of the excited liquid into a glass with a higher fictive temperature. Microscopically, straining causes the structure to dilate, hence “pulls” the structure energetically up the potential energy landscape. Upon further cooling, the resulting excited liquid freezes into an excited glass that exhibits enhanced ductility. We use Zr 44 Ti 11 Cu 10 Ni 10 Be 25 as an example alloy to pull bulk metallic glasses through this excited liquid cooling method, which can lead to tripling of the bending ductility.