Nanocrystalline Soft Magnetic Alloys Two Decades of Progress

Crystal Structure and Magnetic Properties of (Fe,Si,Al)-Based Nanocomposite Magnets Designed for Cryogenic Applications

“…[3] Similar behavior has been observed in other Finemet compositions with and without Al. [4,22,23] From the measured k s values and assuming that the residual stress in the ribbons is r % 1.5 MPa [8] and independent of the composition, the stress anisotropy constant was calculated based on K r = 3/2 AE k s AE r. The results are shown in Figure 7(b) where it can be seen that for all the Al-containing compositions, K r is an order of magnitude or two smaller than the hKi values. Therefore, we can safely assume that the main contribution of the coercivity at room temperature is the average magnetocrystalline anisotropy, hKi.…”

“…In addition to the crystalline phase, some residual amorphous phase exists as indicated from the extra breadth of the {220} fundamental peak (Figure 2(b)). The fact that the D0 3 -Fe 3 (Si,Al) is formed in such a wide range of Fe-SiAl compositions is due to the large solubility of Si and [8,15] which in combination with the coarsening of the grains (narrower diffraction peaks) contributes to the deterioration the soft magnetic properties of the alloy. Based on the breadth of the XRD peaks and using the Scherrer formula, we found that the average grain size for the samples annealed at 823 K (550°C) is between 9 and 11 nm diameter, independent of composition.…”

“…Other materials designed for room temperature use have also been investigated for cryogenic applications, exhibiting varying degrees of degraded performance. [5][6][7][8][9] With all of the materials investigated showing some performance degradation due to the cryogenic environment, it is clear that there is room for new alloys specifically designed for cryogenic temperatures if ferromagnetic materials are going to be considered for use within the cryostat.…”

Crystallization in Rapidly Quenched Fe-B-Si System with Additions of C and Cu

“…The Fe-B-(Si) systems in combination with a small amount of C (as well as with addition of Cu) also have been frequently studied. Alloying with Si and Cu is known to improve magnetic and thermal properties of this system, making these nanostructured materials suitable for many electrical, magnetic and other power applications with lowered material cost [6][7][8][9][10] . These additions into the Fe-B system improve the glass forming ability and the resulting physical properties.…”

“…The ferromagnetic bcc-Fe grains in reduced size well below 100nm are immersed in amorphous matrix [1][2][3][4][5][6][7] . The Fe-B-(Si) systems in combination with a small amount of C (as well as with addition of Cu) also have been frequently studied.…”