Studies of crystallization kinetics of Fe40Ni40P14B6 and Fe80B20 metallic glasses under non-isothermal conditions

A model for the glass crystallization at constant rate heating is presented. Based on the model a technique for determination of the constants involved in the classical equations for the rates of homogeneous nucleation and linear crystal growth is derived. The effect of the heating rate (in the wide range from 2×10-2 to 16 K s-1) on the temperature of crystallization as well as on the average grain size in fully crystallized specimens of Fe40Ni40P14B6 and Fe80B20 metallic glasses has been studied. The values of the interface diffusion coefficient, the rates of nucleation and growth and the volume density of quenched-in nuclei deduced in the present study are in good agreement with those derived from direct observations. It has been confirmed that crystallization of Fe80B20 occurs mainly by the three-dimensional growth of the pre-existing crystallites while the Avrami exponent for the Fe40Ni40P14B6 glass exceeds 4 implying non-steady-state nucleation. It has been demonstrated that the proposed model allows one to generalize the isothermal and non-isothermal kinetic crystallization curves. This revised version was published online in November 2006 with corrections to the Cover Date.