Secondary recrystallization in Fe–6.5 wt% Si alloys by internal friction

Abstract Samples, Fe–6.5 wt% Si, were obtained by quenching from the liquid using the single roller method. Under these conditions, ductile ribbons (20×1×0.05) mm3 were obtained. The initial structure of the as-cast alloy, characterized by X-ray diffraction, was mainly a disordered bcc α phase. Under suitable thermal treatments, annealing at 1373 K during 1 h, the second recrystallization took place. The annealed sample contained precipitates of the ordered B2 Fe–Si phase with a (1 0 0)–(1 1 0) double texture that changed the magnetic properties of the alloy. To analyze the microstructural processes associated with the recrystallization texture, internal friction (IF) spectra were obtained employing an inverted torsion pendulum at frequencies around 1 Hz. The spectra, obtained as a function of the heating temperature, were analysed for the initial as-cast and thermally treated samples. The results show that the recrystallization process is dominated by two grain boundary contributions: a low temperature (∼800 K) peak associated with the free movement of grain boundaries and a peak at around 1000 K where the grain boundary mobility is determined by the interaction with Si solute atoms.