22 July 2005
22 July 2005
A research team from the CAS Institute of Physics has developed a new kind of cerium-based bulk metallic glasses with low glass transition temperature, similar to or lower than that of many polymers.
The polymeric glass is organic materials with a very wide range of application due to its higher glass-forming ability, lower glass transition temperature, and more stable supercooled liquid region than those of metallic glasses.
The thermoplastic nature of common glassy polymers is processed in moulding and imprinting procedure. For metallic glasses, however, engineering application fields are limited because of the limitation of alloy size and the lack of workability and machinability.
While many metallic glasses are now available in bulk form, similar exploitation of their viscous flow is impeded by higher glass transition temperature and lower resistance to crystallization. Yet the mechanical and electrical properties of metallic glasses are, for some applications, far superior to those of polymers.
CAS scientists demonstrate that, in near-boiling water, these materials can be repeatedly shaped, and can thus be regarded as metallic plastics. Their resistance to crystallization permits extended forming times above the temperature and ensures an adequate lifetime at room temperature. Such materials, combining polymerlike thermoplastic behaviour with the distinctive properties of metallic glasses, are highly unusual for metallic alloys and have great potential in applications and can also facilitate studies of the supercooled liquid state.