Thermodynamic Study of Magnetic Field-Enhanced Nanocrystallisation in Amorphous Fe-Si-B(-Nb-Cu)

Abstract

Recent work has shown that annealing amorphous alloys under an applied magnetic field can enhance the fraction of nanocrystalline phase formed and induce a strong texture. This effect has been attributed to the displacement of thermodynamic equilibrium by the energetic contribution from the applied field. In the present paper, an attempt is made to test the validity of this proposition in the Fe-Si-B(-Nb-Cu) system using equilibrium calculations in the framework of the CALPHAD (CALculation of PHAse Diagrams) methodology and a simple estimate of the energy supplied by the field. However, it is found that the magnetic energy term thus obtained is too small to produce the observed change in nanocrystalline phase fraction. Possible reasons for this discrepancy are discussed.

Analysis of Fe78Si9B13 (%at.) ribbons of noncommercial scrap materials produced by melt spinning equipment

“…The first exothermic event is where secrete mostly the amorphous regions rich in Si and B. From the Curie temperature, T c,am ¼ 3981C occurs a rearrangement by Si atoms diffusion in rich Fe amorphous matrix up before the first transformation peak T Fc (Yardley et al, 2007;Chang and Marti, 1983;Rawers et al, 1988). The second heat release event corresponds to a first crystallization (T Fc ) at 5931C, in which the amorphous Si rich region precipitates in a nanocrystalline composite Fe 0.91 Si 0.09 .…”

Effect of high magnetic field on crystallization of Zr46.75Ti8.25Cu7.5Ni10Be27.5 bulk metallic glass

“…In 2004, Wang et al [9] found that the isothermal crystallization of the Zr 62 Al 8 Ni 10 Cu 17 bulk metallic glass was significantly retarded under high magnetic fields. Recently, Tsurekawa and co-workers [11][12][13][14] investigated the effect of magnetic crystallization on texture evolution in Fe-Si-B-(Nb-Cu), and found that a sharp {1 1 0} texture was formed by applying a 6 T magnetic field in a direction parallel to the ribbon surface, meaning that the high magnetic field enhances the development of the {1 1 0} texture in the crystallized ␣-Fe(Si) from Fe-Si-B-(Nb-Cu) amorphous alloys. However, the different mechanisms of the texture formation were suggested for Fe-Si-B and Fe-Si-B-Nb-Cu amorphous alloys, i.e.…”

“…The crystallization behavior of the metallic glasses is affected significantly by various factors, such as annealing temperature and time, external electric field, and high pressure [2][3][4][5][6]. It has been demonstrated that the high magnetic filed is also a powerful tool to affect crystallization process of metallic glasses and texture formation of the crystallized phase [7][8][9][10][11][12][13][14][15]. In 1987, Wolfus et al [7] investigated crystallization kinetics of Fe 83 B 12 Si 5 amorphous ribbon under external magnetic field, and found that the growth rate of magnetic crystalline phases increased with the magnetic field.…”

On the Formation of Nanocrystalline Grains in Metallic Glasses by Means of In-Situ Nuclear Forward Scattering of Synchrotron Radiation

“…Recently, powder prepared from crushed Fe78Si9B13 amorphous ribbons was used for production of transformer cores with improved magnetic properties obtained by suitable annealing [11] which was eventually performed also in an external magnetic field [12]. The effects of a magnetic field on structural transformations in MGs were reported earlier, for example, in [13]. Nevertheless, the studies performed so far have assessed the effects of an external magnetic field from the point of view of the resulting amount of the crystalline phase and/or their magnetic parameters that were reached after heat treatment.…”