Bifurcation theory model for the glass transition

Based on the basic fact that the glass transition is a physical phenomenon which occurs in nonequilibrium solidification conditions, the dynamical pro cess of rapid solidification is discussed by using nonlinear theory and a b ifurcation theory model for the glass transition is established. It is show n that in rapid solidification a multiple steady states phenomenon can take place because of the serious nonequilibrium of the solidification conditio n and the nonlinear coupling between the solidification rate and the solidi fication temperature. and this multiple steady states phenomenon can be und erstood as the glass transition Then, the thermodynamic behavior of the rap id solidification process is analyzed by using nonequilibrium thermodynamic s, and this thermodynamic analysis shows the possibility of the solidificat ion system becoming unstable when the solidification system is far from the equilibrium solidification point to some extent because of the rapid solid ification condition. This model can explain some experimental features of t he glass transition such as the changes of specific heat C-p, expansion coe fficient alpha, diffusion constant D, and viscosity eta and the cooling rat e dependence of T-g. And also, the critical cooling rates of forming glass and the reduced glass transition temperatures of some alloys estimated by t his model are consistent with the experimental results. (C) 1999 Elsevier S cience B.V. All rights reserved.