Formation of monatomic metallic glasses through ultrafast liquid quenching

• Published in: Nature (London) Vol. 512; no. 7513; pp. 177 - 180
• Main Authors: Zhong, Li, Wang, Jiangwei, Sheng, Hongwei, Zhang, Ze, Mao, Scott X.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.08.2014; Nature Publishing Group
• Subjects: 147/143; 639/301/1023/218; 639/301/119/2795; 639/301/357; Alloys; Analysis; Chemical properties; Cooling; Crystallization; Glass; Heat; Humanities and Social Sciences; letter; Metallic glasses; Metals; Methods; multidisciplinary; Quenching; Science; Tantalum; Vanadium; United States
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature13617

Metallic liquids of single elements have been successfully vitrified to their glassy states by achieving an ultrafast quenching rate in a new experimental design, of which the process has been monitored and studied by a combination of in situ transmission electron microscopy and atoms-to-continuum computer modelling. Glass formation in pure metals If the cooling rate is sufficiently fast, it is thought that any metallic liquid can be frozen into a glassy state, which can in turn yield a solid metal with unusual and potentially useful mechanical properties. In practice, such glass formation is mainly limited to metals composed of two or more elements: the cooling rates required to produce a monatomic metallic glass are usually too high to be achieved experimentally. Li Zhong et al . have found a way around this experimental difficulty. They have developed a nanoscale heating system in which a pulsed electrical current can locally melt the metal (briefly forming a small volume of metallic liquid), which then rapidly loses its heat into the surrounding solid bulk and leaves behind a sample of monatomic metallic glass amenable for study of its structure and properties. It has long been conjectured that any metallic liquid can be vitrified into a glassy state provided that the cooling rate is sufficiently high 1 , 2 , 3 , 4 . Experimentally, however, vitrification of single-element metallic liquids is notoriously difficult 5 . True laboratory demonstration of the formation of monatomic metallic glass has been lacking. Here we report an experimental approach to the vitrification of monatomic metallic liquids by achieving an unprecedentedly high liquid-quenching rate of 10 14  K s −1 . Under such a high cooling rate, melts of pure refractory body-centred cubic (bcc) metals, such as liquid tantalum and vanadium, are successfully vitrified to form metallic glasses suitable for property interrogations. Combining in situ transmission electron microscopy observation and atoms-to-continuum modelling, we investigated the formation condition and thermal stability of the monatomic metallic glasses as obtained. The availability of monatomic metallic glasses, being the simplest glass formers, offers unique possibilities for studying the structure and property relationships of glasses. Our technique also shows great control over the reversible vitrification–crystallization processes, suggesting its potential in micro-electromechanical applications. The ultrahigh cooling rate, approaching the highest liquid-quenching rate attainable in the experiment, makes it possible to explore the fast kinetics and structural behaviour of supercooled metallic liquids within the nanosecond to picosecond regimes.