JPH0258342B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a low-loss amorphous alloy that is effective for use in magnetic cores of electromagnetic devices, and more specifically, it has magnetic properties that reduce iron loss and improve thermal stability in the high frequency range, and is suitable for use in high frequency magnetic cores such as switching regulators. The present invention relates to a suitable low-loss amorphous alloy. Conventionally, crystalline materials such as permalloy and ferrite have been used as magnetic cores used in high frequency applications such as switching regulators. However, since permalloy has a low resistivity, iron loss at high frequencies increases. Further, although ferrite has a small loss at high frequencies, its magnetic flux density is as low as 5000G at most, so when used at a high operating magnetic flux density, it approaches saturation, resulting in an increase in iron loss. Recently, there has been a desire to reduce the size of transformers used at high frequencies, such as power transformers used in switching regulators, but in this case, it is necessary to increase the operating magnetic flux density, so ferrite The increase in iron loss is a major practical problem. On the other hand, amorphous magnetic alloys that do not have a crystal structure are
It has recently attracted attention because it exhibits excellent soft magnetic properties such as high magnetic permeability and low coercive force. These amorphous magnetic alloys are based on Fe, Co, Ni, etc., and include P, C, B, B, etc. as amorphous elements (metalloids).
It includes Si, Al, Ge, etc. However, not all of these amorphous magnetic alloys have small iron loss in the high frequency range.
For example, Fe-based amorphous alloys exhibit a very small iron loss of about 1/4 of silicon steel in the low frequency range of 50 to 60 Hz, but they exhibit a significantly large iron loss in the high frequency range of 10 to 50 KHz. However, it is not suitable for use in high frequency ranges such as switching regulators. In addition, in the case of conventional Fe-based amorphous alloys, in order to obtain low loss, it is necessary to heat-treat the alloy in a magnetic field, which makes the processing process complicated, resulting in complicated manufacturing. Due to its low crystallization temperature, it also lacks thermal stability. Conventionally, it has been known that when niobium (Nb) is added during the production of an amorphous alloy, the properties of the resulting amorphous alloy, such as the Curie temperature and saturation magnetization, decrease. However, the iron loss of Nb,
The effect on technical magnetic properties such as thermal stability is unknown. As a result of extensive research to resolve the difficulties associated with amorphous alloys as described above, the present inventors have discovered that Fe
An amorphous alloy made by substituting a portion of Nb with a predetermined atomic percent amount of Nb has low iron loss even in the high frequency range, excellent thermal stability, and can be manufactured by heat treatment in the absence of a magnetic field. We have discovered that this is possible and have developed the amorphous alloy of the present invention. The present invention aims to provide an amorphous alloy having magnetic properties that reduce iron loss and improve thermal stability in a high frequency region. The amorphous alloy of the present invention has the following formula: (Fe _1- aNba) _100- bXb (wherein, X represents B or B and Si (however, Si is 10 atomic% or less), and a and b are each 0.02≦a≦
0.075, representing a number that satisfies the relationship 15≦b≦21. ) is the structural feature shown in the following. In the amorphous alloy of the present invention, Nb is a component that contributes to reducing iron loss in the high frequency region and increasing crystallization temperature, and the amount included: a is expressed in atomic percent, 0.02≦a≦0.075 is set to When a is less than 0.02, the above effect is not so great, and 0.075
If the temperature exceeds 1000, the Curie temperature of the alloy decreases and practicality is lost. X represents an element essential for amorphization,
B or B and Si. When both B and Si are included, the amount of Si is 10 atomic % or less, and if Si exceeds 10 atomic %, the core loss of the obtained alloy increases. The amount of X: b is set in a range that satisfies 15≦b≦21.If b is less than 15, it will be difficult to make the alloy amorphous, and if it exceeds 21, the effect of Nb addition on iron loss will be reduced. It becomes less noticeable. It is preferable that b satisfies 17≦b≦19 because iron loss in the high frequency region is further reduced. The amorphous alloy of the present invention has the above-mentioned Fe, Nb,
After mixing each component (B or B and Si) in a predetermined ratio, it is melted, and this is made into an amorphous alloy by a conventional method (for example, molten metal quenching method), and then this is mixed in a non-magnetic field.
It can be easily produced by heat treatment in a temperature range of 400 to 500°C. The present invention will be explained below based on examples. Example 1 An amorphous alloy having the composition shown in the table was produced by a rolling quenching method. That is, a molten alloy having the above composition is ejected from a quartz tube nozzle between two high-speed rotating rolls under argon gas pressure (1.0 to 2.0 Kg/cm ² ), and the resulting thin body is rapidly cooled to a width of 2 mm thick. A thin strip sample with a length of 30 μm and a length of 10 m was prepared. A 100 cm long piece was cut from this sample, wound around an alumina bobbin with a diameter of 20 mm, and then the whole was heat treated at 430°C for 10 minutes in the absence of a magnetic field. Apply primary and secondary coils to this (number of turns, both 70 times), and measure iron loss (mW/cc) at magnetic flux density Bm = 3KG using a wattmeter at frequencies of 10KHz, 20KHz, 50KHz, and 100KHz. did. In addition, saturation magnetization was measured using a sample vibrating magnetometer, and crystallization temperature was measured using DTA (differential thermal analysis). These results are collectively shown for each composition of amorphous alloy. For comparison, results for Mn-Zn ferrite, which has been conventionally used for switching power supplies, are also shown.

【table】

[Table] As is clear from the results, the amorphous alloy of the present invention has a higher magnetic flux density than ferrite and a lower iron loss than ferrite. Moreover, the crystallization temperature is also increased compared to the amorphous alloy of the comparative example, and its thermal stability is improved. Example 2 An amorphous alloy of (Fe _1- aNba) ₈₁ Si ₆ B ₁₃ was produced in the same manner as in Example 1 by changing the amount of Nb added. The iron loss was measured at frequencies of 10 KHz, 20 KHz, 50 KHz, and 100 KHz under a magnetic flux density of Bm = 3 KG. The results are shown in the figure as a relationship with the amount of Nb added. As is clear from the figure, it was found that the iron loss was particularly small in the range of 0.02≦a≦0.075. As described above, the amorphous alloy of the present invention has a magnetic flux density higher than that of ferrite, a higher iron loss at high frequencies than ferrite, and is low-priced because it is a material mainly composed of iron, and is used in high-frequency transformers, etc. It is industrially useful because it enables miniaturization.

[Brief explanation of the drawing]

The figure is a diagram showing the relationship between the amount of Nb added and the iron loss at each frequency when the magnetic flux density Bm=3KG in the amorphous alloy of the present invention.

Claims (1)

[Claims] Primary formula: (Fe _1- aNba) _100- bXb (wherein, X represents B or B and Si (however, Si is 10 atomic % or less), and a and b are each 0.02≦ a≦
0.075, representing a number that satisfies the relationship 15≦b≦21. ) is a low-loss amorphous alloy. 2. The low-loss amorphous alloy according to claim 1, wherein b is a number satisfying 17≦b≦19. 3 Claims 1 or 2 which are heat-treated at a temperature below the crystallization temperature in a non-magnetic field.
Low-loss amorphous alloy as described in Section 1.