about glass

Journal of Non-Crystalline Solids, 2007

Currently existing expressions of glass forming ability (GFA) have been formulated based on the characteristic temperatures measured from heating of metallic glasses. However, these GFA expressions are not acceptable physically as GFA is defined from cooling of the molten liquid rather than heating of the solid glasses. In consideration of the relationship between the cooling and heating processes, we have derived a new GFA criterion, gc¼(3Tx2Tg)/Tl (Tx: onset crystallization temperature; Tg: glass transition temperature; Tl: liquidus temperature). This criterion correlates very well to the critical cooling rate and agrees exceptionally well with the physically acceptable boundary condition.

Journal of Non-Crystalline Solids, 2011

The Journal of Chemical Physics, 2013

Journal of Non-crystalline Solids, 2015

Thermochimica Acta, 1985

Advances in Physics, 2015

Physical review. E, Statistical, nonlinear, and soft matter physics, 2015

We perform molecular dynamics (MD) simulations of the crystallization process in binary Lennard-Jones systems during heating and cooling to investigate atomic-scale crystallization kinetics in glass-forming materials. For the cooling protocol, we prepared equilibrated liquids above the liquidus temperature Tl and cooled each sample to zero temperature at rate Rc. For the heating protocol, we first cooled equilibrated liquids to zero temperature at rate Rp and then heated the samples to temperature T>Tl at rate Rh. We measured the critical heating and cooling rates Rh* and Rc*, below which the systems begin to form a substantial fraction of crystalline clusters during the heating and cooling protocols. We show that Rh*>Rc* and that the asymmetry ratio Rh*/Rc* includes an intrinsic contribution that increases with the glass-forming ability (GFA) of the system and a preparation-rate dependent contribution that increases strongly as Rp→Rc* from above. We also show that the predict...

2006

Abstract Supercooling of almost any liquid can induce a transition to an amorphous solid phase. This does not appear to be a phase transition in the usual sense—it does not involved sharp discontinuities in any system parameters and does not occur at a well-defined temperature—instead, it is due to a rapid increase in the relaxation time of the material, which prevents it from reaching equilibrium on timescales accessible to experimentation.