Finemet Alloy Research Articles

Effect of co-addition of Nb/Zr on the microstructure and soft magnetic properties of Fe77.5Si11.5B7NbxZr3-xCu1 nanocrystalline alloys

Soft magnetic nanocrystalline alloys, exemplified by FINEMET (Fe73.5Si13.5B9Nb3Cu1), are essential in electronics due to their low coercivity and high permeability. However, demand for miniaturization and enhanced efficiency in power conversion devices necessitates materials with increased saturation magnetization. Given the limited saturation magnetization (1.23 T) of FINEMET alloy, which is attributed to its lower iron content, there has been growing interest in exploring alternative alloys that potentially offer higher saturation magnetization values. The present research introduces a new alloy system that builds on FINEMET by increasing the iron content and meticulously incorporating Nb and Zr in a controlled manner, aiming for a composition that delivers enhanced soft magnetic properties. Alloy ribbons with a newly designed composition of Fe77.5Si11.5B7NbxZr3-xCu1 (x = 0–3 at%) were fabricated via rapid-quenching melt spinning followed by nanocrystallization thermal annealing, and the impact of Nb/Zr content on the magnetic microstructure and magnetic properties was investigated. Strategically distributing both Zr and Nb has been found to effectively suppresses grain growth, enhancing permeability and reducing coercivity and core loss. Remarkably, the Fe77.5Si11.5B7Nb1Zr2Cu1 nanocrystalline ribbon annealed at 580 °C for 10 min demonstrates outstanding soft-magnetic properties with a coercivity of 1.64 A/m and a saturation magnetization of 170.31 emu/g (1.59 T). Furthermore, a high-resolution TEM analysis revealed an impressively small average crystal size of 9.69 nm. It is anticipated that Fe77.5Si11.5B7NbxZr3-xCu1 (x = 0–3 at%) soft magnetic alloys will be broadly applied in power conversion devices such as inductors and transformers, contributing significantly to efficiency and performance enhancements.

Laser powder bed fusion of a nanocrystalline Finemet Fe-based alloy for soft magnetic applications

The aim of this work is to explore the laser powder bed fusion (LPBF) processability window of the nanocrystalline soft magnetic Finemet alloy. With that purpose, several laser power and scan speed values and a meander scanning strategy were probed to process simple geometry specimens. Good dimensional accuracy was obtained within the entire processing window investigated. Relative densities as high as 89% were achieved for processing conditions including high laser power and low scan speeds. The fraction of amorphous phase, which peaked at 49%, was found to be mostly dependent on the scan speed and only slightly influenced by the laser power. The microstructure of the crystalline domains is formed by ultrafine, equiaxed grains with random orientations. Irrespective of the processing conditions, the LPBF-processed samples exhibit a similar saturation magnetization, lower permeability, and higher coercivity than fully amorphous melt-spun ribbons of the same composition. The coercive field of the additively manufactured specimens is fairly independent of the relative density and exhibits a moderate inverse variation with the amorphous fraction. Consistent with earlier works, this study suggests that the average grain size is an important contributor to coercivity.

Orientation dependence of the nanocrystallization and magnetic behavior during annealing of the FINEMET alloy

The microscopic strain evolution and microstructural of FeCuNbSiB amorphous alloy samples were studied under both free and tensile stress annealing conditions using in-situ synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM). An amorphous-nanocrystalline structure was developed in both samples after annealing at 813 K, as the microstrains increased and decreased along the parallel and perpendicular stress directions respectively. The applied stress during annealing imposed limitations on the size of nanocrystals along the tensile and perpendicular stress directions, resulting in smaller sizes compared to those obtained under free annealing conditions, due to the reduction in Gibbs free energy by the applied stress and the subsequent enhancement of nucleation rates. The nanocrystalline size perpendicular to the stress direction was slightly larger than that along the parallel stress direction because the suppression of atomic diffusion perpendicular to the stress direction during crystallization could be favorable for local atomic rearrangement.

Effect of low magnetic field heat treatment process on grain sizes and soft magnetic properties of Finemet cores

In this study, we investigate the effect of low transverse magnetic field annealing on the soft magnetic properties of cores made of industrial Finemet ribbons. The variation of static/dynamic magnetic properties and average grain size of the cores obtained by zero-field annealing (ZFA), secondary-field annealing (SMA) and direct-field annealing (DMA) are studied in detail. It is found that the average grain size obtained by DMA decreased compared to that of the ZFA sample, while the average grain size increased slightly after SMA. The effective permeability (μe) of the ZFA sample after SMA decrease less than that of the ZFA sample with increasing frequency. The μe of the DMA sample decreases significantly at the low-frequency stage but tends to decrease smoothly overall, maintaining high effectiveness at high frequencies magnetic permeability. For example, at 100 kHz, the μe of ZFA at 550 °C temperature is only 0.6 × 104, while the μe of SMA and DMA are 2.0 × 104 and 2.2 × 104, respectively. Meanwhile, the Hc = 1.85 A/m, Br = 0.59 T after ZFA and Hc = 1.67 A/m after DMA show no significant decrease compared to ZFA. While Hc = 0.55 A/m, Br = 0.08 T after SMA. Due to the field anisotropy constant Ku generated after SMA and DMA, the average anisotropy constant is dominated by Ku, the domain structure becomes simple and uniform, and the domain width becomes larger. This leads to a decrease in core losses with increasing frequency and improves the high-frequency characteristics of the core. These results can provide good guidance for performance optimization for Finemet alloys in a wide frequency range.

The influence of Co on the magnetic properties of Fe–Si–B–Nb–Cu system

With development of electric device with high running frequency and large power, classical Finemet alloys are not able to meet their requirements. In order to enhance its saturation magnetization, Fe79.5-xCoxSi6B12Cu1Nb1.5(x = 0, 5, 10 and 15) alloys with good amorphous forming ability had been designed. Furthermore, the strategy of optimizing annealing process was used to enhance the magnetic performance. Results show that when Co atoms entered into nanocrystalline grains in amorphous matrix, the saturation magnetization will enhance from 1.5T to 1.64T with the increase of Co content from 0 at. % to 5 at. %. The annealing temperature window can be widened by about 10K with increasing content of Co. The grain size for alloys with annealed at 823K for 5min is reduced from 40 nm of x = 0–31 nm of x = 5. After optimizing the annealing process, Fe74·5Co5Si6B12Cu1Nb1.5 shows very good saturation magnetization up to Ms = 1.64T, higher than Finemet classical system. Furthermore, the nucleation mechanism and grain growth are investigated to deeply understand the influences factors of magnetic properties. Kinetics of non-isothermal crystallization was also used to take a close look at the relationship between annealing temperature and grain size, which can guide future experiment or industrial production.

Superior high-frequency performances of Fe-based soft-magnetic nanocrystalline alloys

Soft-magnetic nanocrystalline alloys with ultralow power loss are strongly desired for high-frequency power electronic applications. In this work, an industrial ultrathin FINEMET alloy (Fe73.5Si15.5B7Cu1Nb3) ribbon, with 14 μm in thickness, was fabricated by using a roller thermal conductivity-controlled cooling strategy coupled with a bottom blowing argon technique. A magnetic core made of the ultrathin ribbon exhibits excellent high-frequency soft-magnetic properties, with super high permeability of 48,000 at the condition of 1 A/m and 100 kHz and an ultralow core loss of 94 kW/m3 at the condition of 0.2 T and 100 kHz. It is found that the excess loss accounts for the largest proportion in power loss, and this proportion increases with decreasing thickness. The finest grain of nanocrystals, narrowest magnetic domain width, weakest transverse field-induced anisotropy, and considerably increased electrical resistivity (188 μΩ cm) synergistically contribute to the superior soft-magnetic performances at 100 kHz of the ultrathin alloy. This work demonstrates the attractive high-frequency application prospects of ultrathin nanocrystalline alloys in power electronics and information communication due to their excellent performance and huge energy-saving effects, and provides new and comprehensive insights into the power loss of ultrathin nanocrystalline alloys.

The Microwave Absorption in Composites with Finemet Alloy Particles and Carbon Nanotubes.

The absorption of waves of the centimeter and millimeter wavebands in composites with Finemet alloy particles and carbon nanotubes has been studied. It has been established that ferromagnetic resonance and antiresonance are observed in such composites. A method is proposed for calculating the effective dynamic magnetic permeability of a composite containing both a random distribution of ferromagnetic particles and a part of the particles oriented in the same way. In the approximation of effective parameters, the dependences of the transmission and reflection coefficients of microwaves are calculated. It is shown that the theoretical calculation confirms the existence of resonant features of these dependences caused by ferromagnetic resonance and antiresonance. The theory based on the introduction of effective parameters satisfactorily describes the course of the field dependence of the coefficients and the presence of resonance features in these dependences. The frequency dependence of the complex permittivity of the composite is determined. The dependence of the complex magnetic permeability on the magnetic field for millimeter-wave frequencies is calculated.

Mössbauer Spectroscopy with a High Velocity Resolution in the Studies of Nanomaterials.

The present review describes our long experience in the application of Mössbauer spectroscopy with a high velocity resolution (a high discretization of the velocity reference signal) in the studies of various nanosized and nanostructured iron-containing materials. The results reviewed discuss investigations of: (I) nanosized iron cores in: (i) extracted ferritin, (ii) ferritin in liver and spleen tissues in normal and pathological cases, (iii) ferritin in bacteria, (iv) pharmaceutical ferritin analogues; (II) nanoparticles developed for magnetic fluids for medical purposes; (III) nanoparticles and nanostructured FINEMET alloys developed for technical purposes. The results obtained demonstrate that the high velocity resolution Mössbauer spectroscopy permits to excavate more information and to extract more spectral components in the complex Mössbauer spectra with overlapped components, in comparison with those obtained by using conventional Mössbauer spectroscopy. This review also shows the advances of Mössbauer spectroscopy with a high velocity resolution in the study of various iron-based nanosized and nanostructured materials since 2005.

Influence of mechanical stress on magnetization processes in amorphous FINEMET alloy

The influence of mechanical stress on magnetization processes in an amorphous metal alloy have been investigated. The rapidly quenched amorphous metallic ribbons with nominal composition Fe73.5Cu1Nb3Si13.5B9 (precursor of FINEMET) were chosen for this study. The significant differences in the magnetic properties of the studied material were observed at different degrees of mechanical stress applied to the sample. The origin of these effects arises from changes in the dynamics of domain walls. They are primarily caused by variation of their fundamental properties (thickness, energy per unit area of the domain wall) as well as changes in the properties of internal stress areas, which are obstacles to their movement. Impact of stress areas was demonstrated by analysis of influence of mechanical load on the internal demagnetization factor.

Change in Magnetic Anisotropy at the Surface and in the Bulk of FINEMET Induced by Swift Heavy Ion Irradiation.

57Fe transmission and conversion electron Mössbauer spectroscopy as well as XRD were used to study the effect of swift heavy ion irradiation on stress-annealed FINEMET samples with a composition of Fe73.5Si13.5Nb3B9Cu1. The XRD of the samples indicated changes neither in the crystal structure nor in the texture of irradiated ribbons as compared to those of non-irradiated ones. However, changes in the magnetic anisotropy both in the bulk as well as at the surface of the FINEMET alloy ribbons irradiated by 160 MeV 132Xe ions with a fluence of 1013 ion cm−2 were revealed via the decrease in relative areas of the second and fifth lines of the magnetic sextets in the corresponding Mössbauer spectra. The irradiation-induced change in the magnetic anisotropy in the bulk was found to be similar or somewhat higher than that at the surface. The results are discussed in terms of the defects produced by irradiation and corresponding changes in the orientation of spins depending on the direction of the stress generated around these defects.

Comprehensive comparative analysis of Metal-Oxide nanoadditives impacts on Oil-Filled Finemet and Vitroperm alloy core transformers HST concerning nanofluid thermophysical properties accurate estimation

In this paper, a precious analysis is dedicated to thermal properties of three metal oxide-based nanofluid samples as well as their overall effects on a 630 kVA oil natural-air natural three-phase transformer thermal performance. The studied nanofluids comprise a typical mineral oil as the transformer base fluid in which Magnetite, Copper Oxide and Alumina nanoparticles are individually dispersed assuming different solid volume fractions. The suspensions are assessed in terms of density, specific heat capacity, thermal conductivity and viscosity. Furthermore, volume fraction- and temperature-dependent formulas, well-matched with the existing experimental data, are proposed to demonstrate excellent correlation coefficients. Subsequently, the derived formulas are utilized as initial functions for transformer thermal modeling. Actually, to pursue the mentioned approach, performing electromagnetic analyses are indispensable. In this regard, making use of two nanocrystalline alloys, namely, Finemet FT-3 M and Vitroperm 500F as core materials can significantly reduce the transformer resultant losses once compared to the case in which conventional electrical steels are utilized. In this study, to represent the enhancements found in the nanofluid filled transformer perfectly, in addition to analysis of the simulation results against those gained using pure mineral oil, one type of natural ester, Midel 1204, is designated as another option for comparison purposes. It is worth mentioning that by increasing the level of nanoparticles volume concentration, a notable decrease can be observed not only in the oil average temperature, but also in the winding hot spot temperature. The investigations are performed for the transformer under different load rates considering the influence of ambient temperature, and the results accuracy are authenticated through making qualitative comparison against the thermal image of a prototype magnetic nanofluid-immersed transformer. Moreover, the system resultant temperatures are verified to exhibit the finest magnitudes in presence of the studied nanofluids, even lower than that of the ester oil with an extremely high thermal conductivity. Finally, the studied fluids and nanofluids Nusselt numbers versus Rayleigh numbers are attained to demonstrate the results fine agreement with the experimental values, as well as presenting satisfactory enhancement in CuO nanofluid Nusselt number compared to mineral oil-based Alumina/Magnetite/Titania nanofluids results.

Microstructures and Soft Magnetic Properties of Fe73.5-xCu1Nb3Si13.5B9Gdx (x = 0-1.5) Alloys.

In this experiment, the rare earth Gd element was added to Finemet alloy to observe the microstructure and soft magnetic properties. The experimental results showed that the samples with the addition of 0.5% Gd and 1.0% Gd can be quenched and cast normally, and the MS of Fe73Cu1Nb3Si13.5B9Gd0.5 alloy was 10.41% higher than that of Finemet. After annealing, crystal grains of about 10 nm were formed. The μi and μm values of Fe73Cu1Nb3Si13.5B9Gd0.5 alloy were 25.51% and 22.23% higher, respectively, and the coercivity HC was reduced by 12.19% compared to Finemet. At 1 kHz, the μe value of Fe73Cu1Nb3Si13.5B9Gd0.5 alloy at room temperature was 14.57% higher than that of Finemet, while the μe reached 162.34 k and 142.42 k at 90 °C and 150 °C (24% and 29.51% higher, respectively). The Fe72.5Cu1Nb3Si13.5B9Gd1.0 alloy had the best performance at 100 kHz, with higher μe values than Finemet across the ambient temperature range of 30 °C to 150 °C. After tension annealing, the μe values of Fe72.5Cu1Nb3Si13.5B9Gd1.0 alloy were 20–30% higher than those of Finemet.

Microstructures and soft magnetic properties of Fe73.5-xCu1Nb3Si13.5B9Yx (x = 0–1.5) alloys

Adding Y to replace Fe in composition of Finemet alloy, and prepare alloy samples of Fe73.5-xCu1Nb3Si13.5B9Yx (x = 0, 0.5, 1.0, 1.5) to study the structures and soft magnetic properties. After vacuum melting and rapid cooling, the rapidly solidified as-cast alloy ribbons were prepared, and Fe73.5-xCu1Nb3Si13.5B9Yx (x = 0, 0.5, 1.0) as-cast samples have single phase of amorphous structure. So the alloys are amorphous by rapid cooling within the addition of Y less than 1.0%. After annealing, nanocrystalline appeared in the matrix, the nanocrystals are randomly oriented and the grain size of Fe73Cu1Nb3Si13.5B9Y0.5 alloy is around 10 nm, the ordered crystal planes can be observed, it is consistent with α-Fe(Si). From the APT we can see the distribution of elements, Fe and Si are mostly in the grain, Nb and B are in the grain boundary and amorphous phase, and Cu is in clusters. The Fe73Cu1Nb3Si13.5B9Y0.5 alloy has the best soft magnetic properties, with the μi and μm values ​​are 149.93 k and 1213.00 k, respectively, which are 22.19% and 43.72% higher than Finemet. The Fe73Cu1Nb3Si13.5B9Y0.5 alloy also has excellent soft magnetic properties at high temperature, when the ambient temperature at 120 °C and 150 °C, the μe values increased by 42.21% and 40.95% than Finemet at 1 k Hz, respectively; and increased by 14.30% and 19.70% at 10 k Hz. In addition, the Fe72.5Cu1Nb3Si13.5B9Y1 alloy has the lowest coercivity value of 0.40 A/m.

Estimation of Energy Losses in Nanocrystalline FINEMET Alloys Working at High Frequency

Soft magnetic materials are at the core of electromagnetic devices. Planar transformers are essential pieces of equipment working at high frequency. Usually, their magnetic core is made of various types of ferrites or iron-based alloys. An upcoming alternative might be the replacement the ferrites with FINEMET-type alloys, of nominal composition of Fe73.5Si13.5B9Cu3Nb1 (at. %). FINEMET is a nanocrystalline material exhibiting excellent magnetic properties at high frequencies, a soft magnetic alloy that has been in the focus of interest in the last years thanks to its high saturation magnetization, high permeability, and low core loss. Here, we present and discuss the measured and modelled properties of this material. Owing to the limits of the experimental set-up, an estimate of the total magnetic losses within this magnetic material is made, for values greater than the measurement limits of the magnetic flux density and frequency, with reasonable results for potential applications of FINMET-type alloys and thin films in high frequency planar transformer cores.

Microstructural Changes and Magnetic Properties of Nanostructured Fe-Si-B-Cu Ribbon Cores Containing a Small Amount of Ca and Zr

Nanocrystalline Fe-Si-B-Nb-Cu Finemet alloys show low saturation magnetic flux density compared to amorphous Fe-Si-B alloys. In the Fe-Si-B-Cu base amorphous alloys, Cu atoms form clusters which act as heterogeneous nucleation sites for α-Fe crystals. The addition of Ca element atoms, distributed along grain boundaries, helps inhibit grain growth and increase resistivity. These alloys can be crystallized into fine nanograins through proper heat treatment, with increased saturated flux density and decreased core loss. According to previous studies, the addition of Zr element can also reduce nanograin size and suppress grain growth by its distribution mainly along the grain boundaries. In this experiment, the effects of added Ca and Zr on the microstructural changes and magnetic properties of Fe-Si-B-Cu were evaluated in detail. Fe-Si-B-Cu alloys containing Ca, and Zr elements were melt-spun to make rapidly solidified ribbons ~20 μm in thickness. The ribbons were then wound into toroidal shaped ribbon cores and heat treated to obtain the nanocrystalline soft magnetic ribbon cores. The microstructure was observed using TEM, and the magnetic characteristics were evaluated using an B-H meter and impedance analyzer. Based on the results, the FeSi-B-Cu ribbon core containing 0.037 wt.% Ca and 1.68 wt.% Zr was determined to have the lowest core loss among the alloys, when annealed at 440 <sup>o</sup>C for 30 min. It was also confirmed that the added Ca and Zr elements were distributed along the grain boundary, and suppress the growth of crystals. In conclusion, the addition of minor elements Ca and Zr to the nanocrystalline ribbon core was very effective at reducing core loss, and the saturated flux density of the core also increased pronouncedly compared to the Fe-Si-B-Nb-Cu Finemet alloys.

Spark plasma sintering of Fe–Si–B–Cu–Nb / Finemet based alloys

The influence of mechanical alloying (MA) and spark plasma sintering (SPS) processing parameters on the microstructure, magnetic and mechanical properties of Finemet (Fe73.5Cu1Nb3Si13.5B9) type alloys was investigated. Finemet alloy powder was obtained via mechanical alloying of elemental powders for 30 h, 60 h, 90 h, and 120 h with ball to powder ratio (BPR) of 10:1 and 15:1. The milled powders were consolidated using the SPS process. The XRD patterns confirm the presence of the α-Fe3Si phase in all Finemet alloys, also broadening of the (110) peak of α-Fe3Si was observed with increasing milling time. The microhardness of Finemet alloys increases with increase in milling time primarily due to a decrease in grain size. All samples show good saturation magnetization (Ms), 120h sample exhibiting the highest Ms of 166 emu/g, however coercivity increases with increasing milling time. Additionally, α-Fe3Si crystal size decreases with increasing the BPR primarily due to higher impact energy.

Microstructures and soft magnetic properties of Fe73.5Cu1Nb3–xSi13.5B9Yx (x=0–1.5) alloys

Based on composition of Finemet alloy, structures and soft magnetic properties of Fe73.5Cu1Nb3–xSi13.5B9Yx (x = 0, 0.5, 1.0, 1.5) alloys formed by replacing Nb (niobium) by Y (yttrium) were studied in this paper. The research results show that when x = 0 or 0.5, rapidly solidified as-cast alloy is Fe amorphous single-phase structure, and Y atoms are dispersed in matrix; when x = 1.0 or 1.5, crystalline phase precipitates. Fe73.5Cu1Nb3–xSi13.5B9Yx (x = 0, 0.5, 1.0, 1.5) alloys begin to precipitate α-Fe(Si) solid solution phase after crystallization annealing above 480 °C, when x = 0.5, grain size is 12.6 nm, which shows that Y can replace Nb in small amount and refine grain size. Fe73.5Cu1Nb2.5Si13.5B9Y0.5 alloy has excellent soft magnetic properties: μm value is 813.1 × 103, which is 36% higher than that of Finemet alloy; μi value is 154.6 × 103, close to that of Finemet alloy, and Bs and Hc values are 1.24 T and 0.56 A/m, respectively, better than those of Finemet alloy. In addition, Fe73.5Cu1Nb2.5Si13.5B9Y0.5 alloy has excellent soft magnetic properties at high temperature, μe value only reduces by 8.8% at 1 kHz with ambient temperature increased from 30 to 150 °C, and μe value is 128.02 × 103 in 150 °C, which is 15.74% higher than that of Finemet alloy.

Optimum Soft Magnetic Properties of the FeSiBNbCu Alloy Achieved by Heat Treatment and Tailoring B/Si Ratio

To increase the saturation magnetization (Ms) of commercially available soft magnetic Finemet alloys to the level comparable to that of Si-steel and Fe-based nanocrystalline alloys such as Nanoperm, Nanomet, the B or Si content in combination with annealing heat treatment was tailored. The ribbons of Fe95−xSi1BxNb3Cu1 (x = 11, 12, 13) and Fe87−xSixB9Nb3Cu1 (x = 6, 8, 10) were prepared by melt-spinning and annealed at different temperatures to develop nanocrystalline microstructure optimizing the soft magnetic properties. The magnetic properties of the as-spun and annealed ribbons were measured using a vibrating sample magnetometer and AC B-H loop tracer to acquire Ms of above 1.4 T in all as-spun ribbons. Among the alloys, Fe84Si1B11Nb3Cu1 annealed at 545 °C showed the highest Ms of 2 T, which exceeds that of the conventional Finemet and other Fe-based nanocrystalline alloys.

Optimization of the Temperature Stability of Fluxgate Sensors for Space Applications

Fluxgate magnetometers are widely used in many places for the measurement of weak magnetic field, but are sensitive to variations of sensor temperature. Therefore, their stabilization against temperature variation is required especially for outdoor applications. In this work, temperature dependencies of fluxgate sensors having the cores of one homemade, one commercially obtained finemet alloy, and a commercially obtained supermalloy alloy in ribbon form were examined. It was observed that the heat treatments of the studied cores affect the sensitivity of the sensors in different ways. For instance, while the scale factor of the sensor with the core from in-house prepared finemet ribbon increased from 1.19 MV/T to 3.12 MV/T, the scale factor of the sensor with the supermalloy core increases by 20 times in magnitude (41.6 kV/T to 0.92 MV/T) after heat treatment. Our analysis performed in the temperature interval from −50 °C to +85 °C reveals that temperature dependencies of the sensors also show differences depending on the core material. In addition to differences seen on the temperature dependence of the studied cores, the most stable one was the sensor with the heat treated in-house prepared finemet core. The variation of the scale factor in the 135 °C temperature range was 9.8 %. However, by analyzing the temperature dependences of the scale factors we could decrease the error coming from temperature variations to less than 1.0 % in magnitude of the output signal due to the observed linear dependence between the scale factor and the temperature of this sensor.

Effect of Ni substitution to Fe on amorphous nanocrystalline soft magnetic alloy

Improve the Finemet alloy properties by adding Ni elements, and through change the Ni content to control the composition of the alloy system, the alloy has resistance to DC bias characteristics and excellent soft magnetic properties. In the Fe79.5-XSi6B12Cu1Nb1.5NiX (X = 0, 1, 3, 5, 7, 10) alloy, increasing the content of Ni improves the amorphous forming ability of the alloy, and increased thermal stability, the soft magnetic performance has also been improved. with X is about 10 at.% the nanocrystalline core of alloy ribbon annealed show μ is about 3.4 k, and Hc is about 17.51 A/m. The addition of Ni is beneficial to improve the linearity of the hysteresis loop, when the amount of Ni content increases, the linearity is significantly improved, Ni10at.% alloy shows good DC bias resistance in the magnetic field. And tensile stress has also been improved linearity of the hysteresis loop, make the alloy shows good DC bias resistance in the magnetic field of 0–600 A/m. So it has constant magnetic permeability in this magnetic field, the alloys to be a kind of promising material for current transformer with direct current tolerance.