Crystallization of amorphous Fe82P18

Magnetothermal analysis (MTA), high-resolution transmission electron micros copy (HRTEM), and X-ray diffraction (XRD) were employed to investigate the crystallization behavior of amorphous Fe82P18. Three transition stages with distinct microstructures were identified: lamellae of the supersaturated i ntermetallic compound Fe3P with about 5-nm width and varying composition ar e the result of the first transition (stage I); the growth of polygonal gra ins of about 100-nm size from the lamellae marks the second transition (sta ge II); and in the final stage III, grains of alpha-Fe are precipitated. Th e lamellar structure is formed by one-dimensional growth, as concluded from the Avrami exponent n, which was found to lie in the range 1.32 less than or equal to n less than or equal to 1.72. Analysis of the transformation ki netics from the characteristic isothermal transformation curves confirmed t hat the crystallization process depends very sensitively on the heat-treatm ent temperature.