THE FAST COOLING HEATING RATE EFFECTS IN DEVITRIFICATION OF GLASSES -I - NUMBER OF NUCLEATED PARTICLES/

We consider nucleation of crystalline phase in a glass-forming melt wh ich is quenched at some arbitrary rate, S, and then reheated at some o ther (typically smaller) rate. H. In conventional (steady-state) appro aches it is assumed that the nucleation rate is a function of temperat ure only, so that the number of nucleated crystallites is proportional to 1/S + 1/H. We demonstrate, however, that in general the nucleation rate depends on the quench/heating rate and that there exists an S- a nd H-dependent temperature region which effectively does not contribut e to nucleation, so that the aforementioned scaling does not hold. An expression for the non-steady-state nucleation rate is derived analyti cally. In certain cases, the number of nucleated crystallites can be r educed by orders of magnitude compared to the steady-state predictions . The results are tested against numerically tract data obtained from the Turnbull-Fisher nucleation model. (C) 1998 American Institute of P hysics. [S0021-9606(98)50903-8].