Influence of preannealing on the crystallization of Fe75Si15B10 metallic glass

✍ Scribed by Emília Illeková; F.A. Kuhnast; I. Mat'ko; Ch. Naguet

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 668 KB
• Volume: 215
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(96)10375-0

✦ Synopsis

The thermal stability of Fe75SilsB10 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 Surifiach methods.

Both crystallization 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 E* = 395 kJ (g-atom) -1, remain constant.

The first step was related to the crystallization of a-Fe(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 a-Fe was observed during the second step.