Mechanism of thermal stabilization of Fe<inf>89.8</inf>Ni <inf>1.5</inf>Si<inf>5.2</inf>B<inf>3</inf>C<inf>0.5</inf> amorphous alloy

Abstract

Fe89.8Ni1.5Si5.2B3C 0.5 undergoes multi-step structural transformations under thermal treatment. Crystallization process, occurring around 810 K, was separated into two single-step processes, corresponding to formation of α-Fe(Si) and Fe2B crystalline phases, respectively. Significantly higher value of activation energy obtained for the first crystallization step indicate that formation of α-Fe(Si) facilitates the subsequent formation of Fe 2B phase, by increasing in boron content of the amorphous matrix at the crystal/amorphous interphase boundary, while α-Fe(Si) crystallites probably serve as nucleation sites for crystallization of Fe2B phase. Narrow distribution of activation energies for both crystallization steps, obtained using Miura-Maki method, is an indicator of very homogenous structure of as-prepared amorphous alloy. The mechanism of formation of both crystalline phases was modeled using the general Šesták-Berggren model, and it was found that there is relatively small difference between respective reaction mechanisms, which is expected, as both phases crystallize directly out of the amorphous matrix. © 2013 Elsevier B.V. All rights reserved.