2nd Metallic Nanostructure Group Seminar
December 8, 2005, 9:00 am
7th floor seminar room, Sengen
Thermodynamics and Kinetics of Glass Formation and Its Crystallization
K. Mondal
Glass is defined as a state of matter with a lack of long range periodicity of atoms. If a metallic melt is allowed to cool down slowly then below the liquidus temperature thermodynamic driving force for nucleation and growth leads to crystallization in the melt. Transformation of a liquid metallic melt to the glassy phase requires kinetic suppression of nucleation and growth process of crystal by application of proper kinetic constraints. The extent to which the kinetic constraint is to be applied varies from system to system. In the present context, some of the factors deciding glass formation such as Gibb's free energy difference between liquid-crystal, interfacial energy for solid-liquid interface, viscosity of the undercooled liquid, maximum nucleation temperature during crystallization of an undercooled liquid will be focused again for a better understanding of the formation criteria of a glass. A new parameter for the qualitative understanding of glass forming ability of an undercooled liquid has also been found out. In addition to this, an attempt has been made to model to find out some of the kinetic parameters for the formation and devitrification phenomena of glassy alloys.