Study of Nanocrystallization Kinetics in Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 Finemet Type Alloy by Differential Thermal Analysis and Using Different Models

Abstract

The study of the crystallization processes in the FINEMET type nanocrystalline amorphous alloy is interesting not only from the fundamental aspect of establishing reaction mechanism of crystal nucleation and growth, but also from a technological point of view. The process and nature of crystallization phase constitution of nanocrystalline amorphous alloy of composition Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 prepared by rapid quenching method is investigated in the present study. The amorphous nature of the alloy has been verified by x-ray diffraction (XRD). The differential thermal analysis (DTA) experiments were performed at different continuous heating rates of 10, 20, 30, 40 and 50 0 C/min. Two different crystalline phases are observed. The crystallization temperatures, the volume fraction of crystallizations and enthalpies of two different crystalline phases of the alloy have been determined from DTA traces. The dependence of on-set crystallization temperature (T x ) on the heating rate of different phases have been used for the determination of different crystallization parameters such as, the activation energy of crystallization, the order parameter or Avrami exponent (n). The results of crystallization were discussed on the basis of different models such as Kissinger’s approach and modification for non-isothermal crystallization of Matusita in addition to Kolmogorov, Johnson, Mehl, Avrami and Ozawa.