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In order to gain insight into how the addition of Cu element affects the crystallization mechanism of amorphous nanocrystalline alloys and soft magnetic properties, the crystallization behavior of (Fe 0.83 B 0.11 Si 0.02 P 0.03 C 0.01) 100-x Cu x (x = 0 and 0.5) amorphous ribbons was investigated based on kinetic and thermodynamic behavior under non-isothermal and isothermal annealing conditions. The results show that under non-isothermal annealing conditions, the Cu0.5 amorphous ribbon not only favors the formation of the amorphous structure, but also enlarges the temperature window for annealing and improves the thermal stability of the α-Fe(Si) phase. At the same time, the Cu0.5 amorphous ribbon shows slow kinetic and is insensitive to heating rate change during annealing treatment. Under isothermal conditions, the addition of Cu decreases the nucleation activation energy (E n) and increases the growth activation energy (E g). This further indicates that the nucleation of α-Fe(Si) grains is easier than the growth process, which is conducive to the formation of a homogeneous nanostructure and improves the soft magnetic properties of the alloy. Compared to Cu0 amorphous ribbon, it is also shown that the Cu0.5 amorphous ribbon changes the crystallization mechanism from diffusion-controlled one-dimensional to two-dimensional growth when the crystallization volume fraction x is 10–30 vol%. While three-dimensional growth become dominated when x is reaches 60 vol% for both ribbons. Therefore, the kinetics of crystallization as well as microstructure supports that the Cu0.5 ribbon is able to exhibit uniformly fine nanocrystalline structures. Further, the Cu0.5 nanocrystalline ribbon shows a higher B s of 1.85 T and a lower H c of 2.55 A/m, respectively, and the favorable (100) orientation of α-Fe(Si) grains formed after annealing is another factor to increase B s. • The Cu-containing alloy show kinetic insensitivity and is suitable for a high heating rate. • The addition of Cu changes the crystallization mechanism when x is between 10% and 30%. • When the applied magnetic field is ND, precipitation of (100) orientation α-Fe grains favors enhancing B s. • The Cu0.5 alloy show B s of 1.85 T, H c of 2.55 A/m. [ABSTRACT FROM AUTHOR]

• Fe-based amorphous nanocrystalline alloys are studied by molecular dynamics. • The effect of the volume fraction of nanocrystals on the brittleness is investigated. • Classification of samples into three categories based on hardness gradients. • The volume fraction of nanocrystals on brittleness has a critical value. The effect of the volume fraction of body-centered cubic (BCC) crystal in Fe-based amorphous nanocrystalline alloys on room temperature brittleness was investigated via molecular dynamics simulations. Seven model samples with embedded BCC nanocrystal contents ranging from 0 to 33.4 vol.% were obtained. The indentation tests were carried out by spherical rigid indenter to investigate the microstructural evolution and the mechanical properties of those Fe-based amorphous/nanocrystalline alloys in terms of the indentation force, hardness, von Mises shear strain, atomic displacement vector as well as surface morphology. It is found virtually that the plasticity shows a gradient decrease tendency for the three types of samples with 0, less than 16, and more than 20 vol.% nanocrystal, respectively, which is caused by the free volume decreases via monitoring the Voronoi polyhedra. [ABSTRACT FROM AUTHOR]

The effect of P on the glass forming ability, soft magnetic properties and oxidation behavior of Fe 78 B 13 Si 9- x P x ( x = 0–7) amorphous alloys were investigated. It is found that the proper introduction of P, can effectively improve the glass forming ability and stability of supercooled liquid region. Fe 78 Si 4 B 13 P 5 BMG, which exhibits high saturation flux density of 1.56 T, was readily made into rod sample with a diameter of 1.5 mm under air casting atmosphere. P bearing alloys also exhibit excellent soft magnetic properties containing low coercivity of 1.7–2.7 A/m, and high effective permeability of 8200–12,200. Slight oxidation can further improve the coercivity to a lower value of 1.1 A/m and the higher effective permeability to 11,900 for the alloys with P content no more than 3 at. %. Excessive addition of P may deteriorate the glass forming ability, soft magnetic properties and oxidation behavior. Magnetic domain revealing the magnetization process of the amorphous ribbons were characterized to explain the effect of P on magnetic properties and oxidation behavior. [ABSTRACT FROM AUTHOR]

Effects of Fe content on magnetic properties and bending ductility of FeSiBPC amorphous alloy ribbons before and after annealing were systematically investigated. It was found that all alloys had high amorphous forming ability and good soft magnetic properties after annealing. The transition temperature of bending ductility-brittleness decreases much faster than that of soft magnetic properties with the increase of Fe content. It is interesting that alloys with Fe content higher than 80 at.% exhibit good ductility before and after annealing at the optimal condition. The alloy with Fe content of 71 at.% is brittle even at as-spun state. The saturation flux density ( B s ) and coercivity ( H c ) decrease with decrease of the Fe content and deviate from a linear fitting tendency. The temperature asynchronism between magnetic properties and bending ductility of amorphous alloy ribbons was discussed. This work will bring a new perspective to study the annealing induced brittleness and a guidance for the future development of the amorphous alloys. [ABSTRACT FROM AUTHOR]

In the present investigation, the glass forming ability (GFA), thermal stability, and soft magnetic properties of Fe 85 Si 6- x B 8 Cu 1 C x alloys are investigated by the substitution of C for Si. It was found that the GFA of C-containing alloys is remarkably enhanced when a certain amount of Si is replaced by C in a C-free alloy. The temperature interval between the first and second crystallization temperatures is also improved by C addition and reaches a maximum value of 169 °C for the as-spun Fe 85 Si 2 B 8 Cu 1 C 4 amorphous alloy. The Fe 85 Si 4 B 8 Cu 1 C 2 nanocrystalline alloy exhibits the best soft magnetic properties with the highest saturation magnetic flux density (B s) of 1.95 T and the lowest coercivity (H c) of 4.1 A/m, which corresponds to the highest grain number density (N d). The high GFA, large annealing window, low cost, and excellent soft magnetic properties enable the Fe 85 Si 2 B 8 Cu 1 C 4 nanocrystalline alloy as a material with wide applicability. Moreover, this work is highly beneficial in balancing the relationship between a high B s and sufficient GFA in the production of Fe-rich nanocrystalline alloys. • Adding C to Fe-Si-B-C-Cu alloys can improve both the GFA and thermal stability of the as-spun amorphous alloy ribbons. • Addition of appropriate amount of C to Fe-Si-B-C-Cu amorphous alloys can enhance their soft magnetic properties. • As-annealed Fe 85 Si 4 B 8 Cu 1 C 2 alloy exhibits a high B s of 1.95 T and low H c of 4.1 A/m. [ABSTRACT FROM AUTHOR]

• The trajectories for optimized B s and H c determined by both annealing temperature and time were established. • A relatively larger B s up to 1.74 T and lower H c of 4.9 A/m were found for the present alloy compared to the nanocrystalline alloys with similar Fe content. • It is found that the precipitated α -Fe (Si) grain number density is the main factor to determine the B s A (Fe 0.83 B 0.11 Si 0.02 P 0.03 C 0.01) 99.5 Cu 0.5 glass former was formulated based on Fe 83 B 11 Si 2 P 3 C 1 alloy and a new rapid annealing method was employed to investigate both the temperature and time effect on the improvement of soft magnetic properties of the amorphous alloy ribbon. The results show that the interval between the first and second crystallization temperature is enlarged by Cu addition. There exists an optimal annealing time corresponding to the optimal B s and H c for the ribbon annealed at each temperature. The maximum B s up to 1.74 T and the minimum H c of 4.9 A/m were obtained for the ribbon annealed at 426 °C for 150 s. The grain number density of precipitated α -Fe(Si) is the main factor in determining the B s. Compared to other nanocrystalline alloys with similar Fe content, the present alloy ribbon annealed by the new method shows a higher B s and a lowest H c , which makes it a promising soft magnetic material used in the field of electrical and electronic industries. [ABSTRACT FROM AUTHOR]