FeNi50 Soft Magnetic Alloy Powder

FeNi50 soft magnetic alloy powder and ferro alloy powder refers to ferronickel with more than 50% nickel content. It has the characteristics of high permeability, saturation magnetostriction, low hysteresis-energy loss and eddy current loss in alternating flux.

This type of soft magnetic alloy powder is used for instrument transformers, radar pulse transformers, transducers and shielding. This kind of magnetic alloy has many applications and is very popular in the market.

Characteristics

FeNi50 soft magnetic alloy powder is a kind of soft magnetic material. It contains 30-90% nickel and a small amount of other elements. It has high coercivity and permeability in low magnetic field (m).

Spherical FeNi50 alloy powders were fabricated via a novel route based on in-situ interface de-wetting between liquid Fe-Ni alloy and alumina medium. The obtained FeNi50 alloy particles exhibit very good spherical shape according to SEM images. They also show no pores and bulk inclusions in their internal region, as shown by the cross-sectional SEM images.

A series of FeNi50 powder cores were prepared with different alumina and permalloy contents, particle sizes, and insulation amounts. Their magnetic properties were characterized by XRD, EDS, and SEM. The results showed that the permeability and saturation magnetization of the FeNi50 powder cores were increased with higher alumina and permalloy content, particle size and insulation amounts.

Applications

FeNi50 soft magnetic alloy powder is used for a variety of applications, including instrument transformers, radar pulse transformers, transducers, and shielding. Its properties include high permeability, high saturation magnetostriction, low hysteresis-energy loss, low eddy-current loss in alternating flux, and low curie temperature with copper powder.

A novel route for fabricating spherical Fe50Ni50 alloy powders was investigated by in-situ interface de-wetting between liquid Fe-Ni alloy and alumina particles. This de-wetting process was successful and the resulting spherical Fe-50Ni50 alloy powders displayed good spherical shape.

The spherical Fe-50Ni50 powders exhibited a slightly decreased saturation magnetization compared to the pre-alloy powder directly reduced from oxides, but they still possessed a soft magnetic property. This can be attributed to the phase composition and microstructure of the spherical Fe-50Ni50 particles. They also exhibited a relatively stable room temperature magnetic hysteresis loop. These results provide a valuable insight into the feasibility of using spherical Fe-50Ni50 as a soft magnetic core material.

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Technical Data

The technical data associated with FeNi50 soft magnetic alloy powder are based on a variety of tests, including scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), Fourier transform infrared spectroscopy analysis, and annealing. These test methods provide information about the morphology, composition, and microstructure of the alloy powders.

Compared with the raw Fe-Si-Cr powder, the phosphated and coated samples have a higher resistivity and lower hysteresis loss and eddy current loss. Moreover, the characteristic peak intensity of the a-Fe phase shows a downward trend as the coating content increases from 0 to 1.0 wt%.

The hysteresis loops of the phosphated and coated samples P0P6 are shown in Figure 5. In comparison with the raw powders, the Ms of the coated Fe-Si-Cr sample is lower than that of the raw powders (127.3 emu*g-1). This decrease indicates that the phosphating and coating processes remove some non-magnetic insulating layers from the Fe-Si-Cr powder and improve the magnetic properties of the composite powders.

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Production Process

Soft magnetic alloy powders are fabricated by a variety of techniques with termal aerosol. These include reduction of pre-alloy powders, in-situ fabricating spherical Fe50Ni50 alloy powders and introducing surface coatings to improve permeability or reduce eddy current loss.

For example, a recent study improved permeability and core losses of Fe-Si-B based amorphous powders by adding micron-sized ferromagnetic crystalline metal particles (Permalloy). These composite powders have the highest permeability and low coercivity when compared to the Fe based amorphous powder.

In another work, spherical Fe50Ni50 powders were fabricated by in-situ de-wetting the liquid Fe50Ni50 alloy from an alumina surface with hydrogen reduction and subsequent heat treatment. These spherical alloy powders showed good morphology and no pores or bulk inclusions on the alumina surface.

These alloy powders have a slight decrease of saturation magnetization when compared with the pre-alloy powders due to the alumina coatings, but they still exhibit a good soft magnetic property. These spherical Fe50Ni50 Fe-Si-B amorphous powders have a high density, low coercivity and low hysteresis loss.