Beating Crystallization in Glass-Forming Metals by Millisecond Heating and Processing

• Published in: Science (American Association for the Advancement of Science) 2011-05, Vol.332 (6031), p.828-833
• Main Authors: Johnson, William L., Kaltenboeck, Georg, Demetriou, Marios D., Schramm, Joseph P., Liu, Xiao, Samwer, Konrad, Kim, C. Paul, Hofmann, Douglas C.
• Format: Article
• Language: English
• Subjects: Alloys; Amorphous materials; Condensed matter: structure, mechanical and thermal properties; Cooling; Cross-disciplinary physics: materials science; rheology; Crystallization; Electrodes; Enthalpy; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Glass transitions; Glasses (including metallic glasses); Heat; Heating; Liquids; Materials science; Metallic glasses; Metals; Physics; Polymers; Resistance heating; Rheology; Silicates; Specific materials; Specific phase transitions; Stability; Temperature scales; Thermoplastics; Viscosity
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1201362

The development of metal alloys that form glasses at modest cooling rates has stimulated broad scientific and technological interest. However, intervening crystallization of the liquid in even the most robust bulk metallic glass-formers is orders of magnitude faster than in many common polymers and silicate glass-forming liquids. Crystallization limits experimental studies of the undercooled liquid and hampers efforts to plastically process metallic glasses. We have developed a method to rapidly and uniformly heat a metallic glass at rates of 10⁶ kelvin per second to temperatures spanning the undercooled liquid region. Liquid properties are subsequently measured on millisecond time scales at previously inaccessible temperatures under near-adiabatic conditions. Rapid thermoplastic forming of the undercooled liquid into complex net shapes is implemented under rheological conditions typically used in molding of plastics. By operating in the millisecond regime, we are able to "beat" the intervening crystallization and sucessfully process even marginal glass-forming alloys with very limited stability against crystallization that are not processable by conventional heating.