Influence of preannealing on the crystallization of Fe75Si15B10 metallic glass

The thermal stability of Fe75Si15B10 metallic ribbon was analyzed. The kinetics of the two-step crystallization of as-quenched and isothermally preannealed samples was studied by differential scanning calorimetry using various heating rates and the Kissinger, isoconversional and Suriñach methods. rystallization stages are characterized by the Johnson-Mehl-Avrami kinetic law. The first step is dependent on both the heating rate and the preannealing. After sufficient heat treatment, the Avrami exponent decreases from 2.5 to 1.5, and the activation energy decreases to the value characteristic for the crystal growth mode. The second-step Avrami exponent n2 = 3, and the activation energy E2* = 395 kJ (g-atom)-−1, remain constant. rst step was related to the crystallization of αFe(Si) and Fe3Si, during which some of these primary crystals nucleate heterogeneously on the Fe3B cores. The eutectic decomposition of Fe3B into stable Fe2B and αFe was observed during the second step.