JPH06346179A - Metal powder for iron-nickel type sintered compact, iron-nickel type sintered compact, and production thereof - Google Patents

Abstract

PURPOSE:To minimize energy loss at the time of vibration in a low-freauency region by subjecting a molded body of a kneaded material consisting of an Ni alloy powder of prescribed conditions, containing prescribed percentages of Ni and Fe, and an organic binder to sintering at a temp. slightly lower than the melting point of this alloy powder. CONSTITUTION:An alloy having a composition consisting of, by weight, 10-60% Ni and the balance Fe is melted. This Fe-Ni alloy is formed into powder, in which average grain size, carbon content, and oxygen content are regulated to <=15mum, <=0.1%, and <=0.5%, respectively. Then, this alloy powder is kneaded with an organic binder, which is molded and degreased. Subsequently, sintering is done at a temp. lower by 20-100 deg.c than the melting point of this alloy powder, By this method, the Fe-Ni type sintered compact minimal in energy loss at the time of vibration in a low frequency region of <=100KHz can be obtained.

Description

Detailed Description of the Invention

[0001]

The present invention relates to iron energy loss is small at the time of vibration of the following low-frequency region 100kH _Z - about nickel (Fe-Ni) sintered body.

[0002]

2. Description of the Related Art Fe-Ni based alloys are ferromagnetic metal materials having excellent magnetic properties, and for example, high magnetic permeability materials such as permalloy (Fe-78Ni, Fe-45Ni) and magnetostrictive effects. A magnetostrictive material represented by an amber alloy (Fe-36Ni) having a low coefficient of thermal expansion can be given. Among them, a metal material having a low thermal expansion is used in a precision machine part that requires high dimensional accuracy.

Since Fe-Ni-based metallic materials contain a large amount of retained austenite after cooling during their production, they are inferior in machinability. Therefore, in the production of complex shaped parts, powder metallurgy capable of forming and sintering in a net shape Is used. In addition, magnetic materials are required to have low energy loss in addition to good magnetic properties.
Since it has a low coefficient of thermal expansion, it is used for parts of ultrasonic motors, etc. However, when vibration damping capacity is large, energy loss due to vibration becomes large and efficiency is reduced.

[0004]

The loss of energy due to this vibration greatly depends on the frequency and increases as the frequency increases. Therefore, ultrasonic motors and the like are required to have small energy loss due to vibration in a high frequency range. Generally, such energy loss mainly consists of hysteresis type loss and eddy current loss. In the frequency range exceeding 100KH _Z, since the interior of the eddy current loss becomes large unusable because the electrical resistance is too small in metallic magnetostrictive material, a large ceramic electric resistance is used. On the other hand, in the 100KH _Z following low frequency range, there hysteresis loss should consider at the same time as the eddy current loss. The hysteresis type loss is an energy loss due to the movement of the domain wall due to the fluctuation of the magnetic field, and the defects inside the material have a great influence. Therefore, in the sintered body, the defects existing inside affect the magnetic characteristics or the energy loss, and in the magnetostrictive material which is a sintered material, the energy loss is presently worse than that of the ingot material. Normally, the allowable limit of the industrially applicable characteristics of this type of sintered body is that the vibration loss coefficient is required to be 1.5 times or less that of the ingot material.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies on the properties of the metal powder for a Fe--Ni system sintered body that affect the energy loss and the sintering conditions for sintering the powder. As a result, in order to produce a Fe-Ni-based sintered body having a small energy loss by the powder metallurgy method, it is desirable to increase the sintering density and reduce the internal voids without coarsening the crystal grain size. With the knowledge obtained, the present invention has been completed by finding conditions for efficiently producing such a sintered body.

That is, the Fe-Ni system sintered body according to the present invention is as follows.

Ni is 10 to 60 wt% in the raw metal powder,
A powder of an Fe-Ni alloy, the balance of which is Fe,
The powder has an average particle size of 15 μm or less and a carbon content of 0.1.
wt% or less and the oxygen content is 0.5 wt% or less.

The sintered body is a sintered body of Fe-Ni alloy powder containing 10 to 60 wt% of Ni and the balance of Fe, and has a sintering density ratio of 98% or more and an average crystal grain size of 20.
It is 0 μm or less.

The manufacturing method is as follows: a) Fe containing 10 to 60 wt% of Ni and the balance of Fe
-Ni-based alloy powder having an average particle size of 15 µm or less, a carbon content of 0.1 wt% or less, and an oxygen content of 0.5% or less is used as a raw material, and b) the alloy powder is an organic binder. And kneading, molding, and degreasing, and c) sintering the degreased body at a temperature 20 to 100 ° C. lower than the melting point of the alloy.

The present invention will be specifically described below.

In the present invention, Fe is used as the raw metal powder.
When using a mixed powder of Fe powder and Ni powder, Ni-based alloy powder is used, and Ni diffuses into Fe at the initial stage of sintering to form large internal pores around the original Ni powder. Therefore, Ni impairs the sinterability, and it is impossible to obtain a high-density sintered body having a sintering density ratio of 98% or more.

Further, in the alloy composition of the raw material alloy powder,
Ni is 10 to 60 wt% and the balance is Fe.
If the content is less than 10 wt% or more than 60 wt%,
This is because the electric resistance of the obtained sintered body becomes small and the energy loss in the high frequency range becomes large.

Regarding the properties of the raw material alloy powder, when the raw material alloy powder is a fine powder having an average particle diameter of 15 μm or less, the internal pores of the sintered body are completely spherical, so that the coarsening of crystal grains is suppressed. To be done.

Further, in order to suppress the decrease in the density of the sintered body due to the confinement of the gas generated by the reaction between C and O during sintering, the C content is 0.1 wt% or less and the O content is 0.1% or less. It is required to be 5 wt% or less.

The degreased compact obtained by kneading the raw material alloy powder with an organic binder, molding by injection molding, etc., and degreasing is preferably sintered at a temperature as high as possible within a range not causing recrystallization, Therefore, in the present invention, sintering is performed at a temperature 20 to 100 ° C. lower than the melting point of the alloy. By sintering within this temperature range, a sintered body having a sintering density ratio of 98% or more and an average crystal grain size of 200 μm or less can be obtained without recrystallization.

In the present invention, the organic binder added to the raw material alloy powder may be one commonly used for metal powder injection molding, for example, a binder comprising a thermoplastic resin, a wax and a plasticizer, and the addition amount thereof is 40 to 60 vol%. Is preferred. For kneading the organic binder and the raw material powder, a batch type or continuous type kneader is used.

In the present invention, it is desirable that degreasing be performed in an inert gas atmosphere, under reduced pressure, or after depressurization in an inert atmosphere to prevent oxidation during degreasing.

In the present invention, as a sintering atmosphere, vacuum or hydrogen gas is used in a temperature range of 1100 ° C. or lower where the reaction of C and O is completed, and argon or vacuum is used in a temperature range higher than that.

The Fe according to the present invention thus obtained
As shown in FIG. 1, which shows the relationship between the frequency and the vibration loss coefficient at 7.7 kH _Z and 20 kH _Z in the Fe-36 wt% Ni alloy sintered body, the —Ni-based sintered body has the same composition. Compared with the ingot material, the energy loss of the sintered body increases as the density ratio of the sintered body decreases. This is because defects such as internal holes existing inside the sintered body impede movement and rotation of the domain wall, which increases hysteresis loss. Further, if the relative density is 98% or more, the loss coefficient can be 1.5 times or less that of the ingot material. Fe-Ni-based sintered body according to this way the present invention will become as energy loss during the vibration of the 100KH _Z following low frequency range is small, will have a wide utilization range as such magnetostrictive material.

[0020]

The present invention will be described in more detail with reference to the following examples.

A powder having the characteristics described in the raw material metal powder of Table 1, a thermoplastic resin (acrylic resin + ethylene resin) wax, and an organic binder in an amount of about 50 vol% consisting of a plasticizer are used in a pressure kneader type. The kneading machine was used for kneading. The resulting kneaded product was 3 × 10 by an injection molding machine.
After molding into a flat strip test piece of x55 mm, it was degreased in a nitrogen gas atmosphere up to 500 ° C at a heating rate of 1 ° C / min.
The obtained degreased body was sintered at the temperature shown in Table 1 to obtain a sintered body. The physical properties of this sintered body are the sintered density ratio, the average crystal grain size,
The electric resistance was measured and the results shown in Table 1 were obtained.

[0022]

[Table 1]

The effects of the powder characteristics and the sintering temperature on the density of the sintered body and the average crystal grain size are as follows. First, whether the mixed powder is used as a raw material or whether C exceeds 0.1 wt%. When powder having a composition in which O exceeds 0.5 wt% is used as a raw material (melting point of Fe—Ni alloy-sintering temperature)> 100 ° C.
In the case of, the sintered density ratio is smaller than 98%. Also, (F
When the melting point of the e-Ni alloy system-the crystal temperature) <20 ° C,
The average crystal grain size exceeds 200 μm, and the crystal grains become coarse. Further, the electric resistance greatly varies depending on the Ni content, and when Ni <10 wt% or Ni amount> 60 wt%, the electric resistance becomes 30 μΩcm or less and the AC characteristics deteriorate.

The measured vibration loss factor at 20 kHz _Z perform further measurements of the vibration loss factor for the sintered body having the same composition ingot material of the present invention and comparative examples by a mechanical impedance method. The results are shown in Table 2. It can be seen that the vibration loss coefficient of the sintered body of the present invention is 1.5 times or less that of the ingot material, which is lower than that of the comparative example.

[0025]

[0026]

According to the present invention, it is possible to small Fe-Ni-based sintered body energy loss under vibration of 100KH _Z following frequency range produced by powder metallurgy.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between frequency and vibration loss coefficient of a Fe-36Ni alloy sintered body.

Claims (3)

[Claims] 1. An iron-nickel alloy powder comprising 10 to 60 wt% of nickel and the balance being iron, the powder having an average particle size of 15 μm or less, a carbon content of 0.1 wt% or less, and an oxygen content. A metal powder for an iron-nickel-based sintered body, characterized in that the amount thereof is 0.5 wt% or less. 2. A sintered body of an iron-nickel alloy powder containing 10 to 60 wt% of nickel and the balance being iron, and the sintered density ratio thereof is 98% or more and the average crystal grain size is 200 μm or less. An iron-nickel based sintered body characterized by: 3. An iron-nickel alloy powder comprising: 10) 60% by weight of nickel and the balance being iron, and having an average particle size of 1
Starting from an alloy powder having a carbon content of 5 μm or less, a carbon content of 0.1 wt% or less, and an oxygen content of 0.5% or less, (b) kneading the alloy powder with an organic binder, molding, and degreasing; ) Sintering the degreased body at a temperature 20 to 100 ° C. lower than the melting point of the alloy, the method for producing an iron-nickel based sintered body.