E0205

Thermodynamics and Kinetics of Bulk Metallic Glass Forming Liquids. Ralf Busch, W.M. Keck, Laboratory of Engineering Materials, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 USA

During the past few years, a number of multicomponent alloy families have been developed in which the liquid alloys form metallic glass at cooling rates below 100 K/s and as low as 1 K/s. This allows for the processing of bulk metallic glasses with samples ranging between 1 and 30 mm in the smallest dimension. Typical alloys are Zr-Ti-Cu-Ni-Be or Zr-Al-Cu-Ni. The undercooled liquids show remarkable resistance with respect to crystallization. This permits studies of thermophysical properties, glass transition, and the crystallization behavior in time and temperature windows that have not been accessible in the past for metallic systems. Results on thermodynamics, viscosity, liquid phase separation, crystallization, and TTT-diagrams have been obtained. These studies reveal the thermodynamic, kinetic, and topological factors that contribute to the higher glass forming ability of bulk metallic glasses compared to previously known metallic glass formers.

Engineering properties, potential applications, as well as future research directions will be discussed. Composites of ceramics or crystalline metals in a bulk metallic glass matrix can be successfully processed, due to the high intrinsic resistance of bulk metallic glasses to heterogeneous nucleation and crystal growth.