Structural transformations of Fe<inf>81</inf>B<inf>13</inf>Si <inf>4</inf>C<inf>2</inf> amorphous alloy induced by heating

Abstract

Thermal stability and crystallization of the Fe81B 12Si4C2 alloy were investigated in the temperature range 25700 °C by the XRD and Mssbauer analysis. It was shown that on heating the as-prepared amorphous Fe81B12Si 4C2 alloy undergoes thermal stabilization through a series of structural transformations involving the process of stress-relieving (temperature range 200400 °C), followed by a loss of ferromagnetic properties (Curie temperature at 420 °C) and finally crystallization (temperature range 450530 °C). The process of crystallization begins by formation of two crystal phases: Fe3B and subsequently Fe 2B, as well as a solid solution α-Fe(Si). With increase in annealing temperature, the completely crystallized alloy involved only two phases, Fe2B and solid solution α-Fe(Si). XRD patterns established a difference in phase composition and size of the formed crystallites during crystallization depending on the side (fishy or shiny) of the ribbon. The first nuclei of the phase α-Fe3Si were found on the shiny side by XRD after heat treatment even at 200 °C but the same phase on the fishy side of ribbon was noticed after heat treatment at 450 °C. The largest difference between the contact and free surface was found for the Fe2B phase crystallized by heating at 700 °C, showing the largest size of crystallites of about 130 nm at 700 °C on the free (shiny) surface. © 2010 Elsevier B.V. All rights reserved.