He Men

High Bs Fe84−xSi4B8P4Cux (x = 0 – 1.5) nanocrystalline alloys with excellent magnetic softness

The magnetic properties of annealed Fe84−xSi4B8P4Cux (x = 0, 0.5, 0.75, 1.0, 1.25, 1.5) soft-magnetic alloys prepared by melt–spinning were investigated. In this alloy system, the appropriate addition of the Cu element promotes the precipitation of α-Fe(Si), as well as inhibits the precipitation of other phases. The saturation magnetic flux density Bs increases and the coercivity Hc markedly decreases simultaneously with increasing Cu content until x = 1.25. The Fe82.75Si4B8P4Cu1.25 alloy annealed at 873 K for 1.8 ks shows a high Bs of 1.83 T and excellent soft-magnetic properties such as a low Hc of 2.1 A/m and a high effect permeability of 31 600. It is found that a 1%–1.25% addition of Cu is effective for the improvement of soft-magnetic properties for the present alloy system.

Soft-ferromagnetic bulk glassy alloys with large magnetostriction and high glass-forming ability

The effect of Dy addition on the glass-forming ability(GFA),magnetostriction as well as soft-magnetic properties and fracture strength in FeDyBSiNb glassy alloys was investigated. In addition to the increase of supercooled liquid region from 55 to 100 K, the addition of Dy is effective in approaching alloy to an eutectic point and increasing the saturation magnetostrction (λ s ). Accordingly, bulk glassy alloy (BGA) rods with diameters up to 4 mm were produced, which exhibit a large λ s as high as 65×10-6. Besides, the BGA system exhibits superhigh fracture strength of 4000 MPa, combined with good soft-magnetic properties.

High-entropy bulk metallic glasses as promising magnetic refrigerants

In this paper, the Ho20Er20Co20Al20RE20 (RE = Gd, Dy, and Tm) high-entropy bulk metallic glasses (HE-BMGs) with good magnetocaloric properties are fabricated successfully. The HE-BMGs exhibit a second-order magnetic phase transition. The peak of magnetic entropy change ( ΔSMpk) and refrigerant capacity (RC) reaches 15.0 J kg−1 K−1 and 627 J kg−1 at 5 T, respectively, which is larger than most rare earth based BMGs. The heterogeneous nature of glasses also contributes to the large ΔSMpk and RC. In addition, the magnetic ordering temperature, ΔSMpk and RC can be widely tuned by alloying different rare earth elements. These results suggest that the HE-BMGs are promising magnetic refrigerant at low temperatures.

Fe-based nanocrystalline FeBCCu soft magnetic alloys with high magnetic flux density

In this study, the magnetic properties and crystalline behavior of Fe84−xB10C6Cux (x = 0–1.3) alloys prepared by annealing the melt-spun ribbon have been investigated. A Cu element was added to this system with the aim of decreasing the coercivity because the addition of Cu clusters prior to the crystallization stimulates the nucleation of α-Fe primary crystals, which greatly influences the final microstructure. It is found that in the Fe84−xB10C6Cux alloy system, the coercivity decreases with increasing x and exhibits a minimum at around x = 1.0. When x = 1.0, the alloy exhibits excellent magnetic properties after the appropriate heat treatment with a high Bs of 1.78 T, low Hc of 5.1 A/m, and low core loss less than 4.3 W/kg at 1.0 T and 400 Hz that is about 55% of that of oriented Si-steel. These results indicate that the application of this alloy to power transformers will produce very large energy savings.

Effect of P to B concentration ratio on soft magnetic properties in FeSiBPCu nanocrystalline alloys

The effects of P to B concentration ratio on magnetic properties and microstructure in annealed Fe82.65Si2B14−xPxCu1.35 (x = 1−6) soft magnetic alloys prepared by melt spinning were investigated. The proper substitution of B with P was found to be effective in decreasing grain size in the alloys annealed at 793 K for 120 s. The coercive force Hc markedly decreases from 67.1 to 1.1 A/m and the saturation magnetic flux density Bs shows a slightly decreasing trend with increasing P content from x = 1 to 5. The nanocrystalline Fe82.65Si2B9P5Cu1.35 alloy, with an average grain size of 15 nm, shows a combination of high Bs and excellent soft magnetic properties.

Interactions of Shear Bands in a Ductile Metallic Glass

Shear bands play a key role in the plastic deformation of metallic glasses (MGs). Even though there are extensive studies on the initiation and propagation of shear bands, the interactions among them have not been systematically studied yet. The interactions between the primary shear bands (PSBs) and secondary shear bands (SSBs) in a ductile Zr-based MG were studied. The residual stress near PSBs can deflect the propagation direction and reduce the propagation velocity of SSBs, which contributes to the plasticity and toughness of the MG. It was demonstrated that the probability and strength of the interactions between PSBs and SSBs would become stronger for MGs with larger Young s modulus and smaller shear modulus, i. e., larger Poisson s ratio. These results are valuable in understanding the plastic deformation of MGs and may be helpful in designing new MGs with desirable mechanical properties.