WO2017064641A1

WO2017064641A1 - Method for studying the evolution of the magnetic and structural properties of soft amorphous and nanocrystalline magnetic materials and apparatus using said method

Info

Publication number: WO2017064641A1
Application number: PCT/IB2016/056130
Authority: WO
Inventors: Javier Alberto MOYA
Original assignee: Consejo Nacional De Investigaciones Científicas Y Técnicas (Conicet); Universidad Catolica De Salta; Inis Biotech Llc
Priority date: 2015-10-14
Filing date: 2016-10-13
Publication date: 2017-04-20
Also published as: AR102270A1

Abstract

The invention relates to a device for studying the evolution of the magnetic and structural properties of soft amorphous and nanocrystalline magnetic materials, said device being characterised in that it comprises at least one first group of windings for determining hysteresis cycles, at least one second group of windings for determining magnetic permeability, an arrangement for holding the sample in the form of a belt, an energy source for the annealed products, a current and/or voltage amplifier, an associated hardware and a software. The invention relates to a method for studying the evolution of the magnetic and structural properties of soft amorphous and nanocrystalline magnetic materials, which, combined with the use of the device, allows the almost simultaneous measurement of various properties (currently we can mention three magnetic properties and one electrical one at ambient temperature and at high temperature almost simultaneously).

Description

METHOD FOR THE STUDY OF THE EVOLUTION OF MAGNETIC AND STRUCTURAL PROPERTIES OF AMORPHOUS AND NANOCRISTALINAL MAGNETIC MATERIALS AND APPARATUS THAT USES SUCH METHOD.

FIELD OF THE INVENTION

The present invention relates to a method for the study of the evolution of the magnetic and structural properties of amorphous and nanocrystalline soft magnetic materials and the apparatus employing said method.

BACKGROUND OF THE INVENTION

Usually, the Magnetization measurements in temperature and coercive field are carried out in equipment called VSM (Vibrating Sample Magnetometer) with the incorporation of an oven to provide temperature.

These equipments usually produce more powerful magnetic fields than those of the present equipment because they are also used for hard magnetic materials (magnets) and can have implements for low temperature, for example. [Four. Five]. The fundamental differences are that the present invention allows the magnetic study in frequencies, allows the measurement of the electrical resistivity of the sample and allows measuring a point at high temperature and the next one at room temperature, due to the low inertia of the system, all these measures almost simultaneously, and, in this way, much more information is obtained on a single sample. US 5069428, related to "A: Method and apparatus of continuous dynamic joule heating to improve magnetic properties and to avoid annealing embrittlement of ferro-magnetic amorphous alloys", proposes an equipment and method for annealing amorphous and nanocrystalline tapes by the Joule heating technique that at the same time provides an improvement in the magnetic and mechanical properties.

Regarding the technique of heat treatment by effect "Joule Heating" on these materials, the first works began to be developed in 1983 [1] applying to the current tapes of up to 5 A for times of up to 20 s, in order to relax the material stresses still in amorphous state and thus improve their magnetic properties. Subsequently, new work began to be developed with this type of treatment, at different currents and application times, which were also used to achieve the nanocrystallization of some materials. In 1987, this technique began to be used, not only to obtain some structural relaxation or crystallization, but to study the evolution of the structure with the temperature generated by Joule heating by measuring the electrical resistance as it increased linearly the current applied on the sample [2]. This type of treatment is very scarce in the literature and particularly only two articles have been found on amorphous systems [2], [3], and two others on nanocrystalline systems [4], [5].

On the other hand, and in relation to the combined use of various techniques or experiments for the study of materials, it is particularly common in these amorphous and nanocrystalline metal alloys to determine the variation of two or more properties with the annealing temperature (and with different types of annealing) and compare them in a single graph either to identify structural changes or rearrangements or to determine the optimal annealing conditions properties. The scientific literature is full of such examples as being, the three articles to which we will briefly refer to below:

(1) In reference [6], the authors measured the magnetic permeability (□ r ^Amb ) and electrical resistance (R ^Amb ) properties, both at room temperature, on nanocrystalline tapes, after several annealing with traditional techniques . Then they perform a confrontation of both in Fig. 2 of said reference.

(2) In Reference [7], the authors compare, on the same alloy, curves of magnetization in temperature (Ms ^Temp ) and electrical resistance to temperature (R ^Temp ) obtained in different works (and, consequently, not in simultaneously on the same tape). Said comparison is found in Fig. That of said reference.

The experimental difference between these two mentioned articles is that, in addition to determining different properties to compare them with the electrical resistance, the first one carries out the measurements at room temperature while in the second the measurements are at temperature.

(3) In Reference [8], the authors develop a device to determine the hysteresis cycles of nanocrystalline tapes as a function of temperature and annealing time obtaining the values of Saturation Imanation (Ms ^Temp ), Coercive Field (Hc ^Temp ) and the Saturation Imanation relationship over the remaining Imanation. These results are plotted in Fig. 5 of said reference.

The present invention can determine in a single experiment these four mentioned properties, and in the ambient temperature conditions (Dr ^Amb , R ^Amb , Ms ^Amb and Hc ^Amb ) and at the test temperature (Dr ^Temp , R ^Temp , Ms ^Temp and Hc ^Temp ) almost simultaneously. SUMMARY OF THE INVENTION

It is then an object of the present invention to provide a method for the study of the evolution of the magnetic and structural properties of amorphous and nanocrystalline soft magnetic materials, which allows several properties to be measured almost simultaneously (currently we can mention three magnetic properties and an electric at room temperature and high temperature almost simultaneously).

It is therefore an object of the present invention to provide a device for the study of the evolution of the magnetic and structural properties of amorphous and nanocrystalline soft magnetic materials, the device being characterized in that it comprises at least a first set of at least one second set of coils, a sample clamping arrangement in the form of a tape, an energy source for annealing, a current amplifier, an associated hardware and software.

DESCRIPTION OF THE DRAWINGS

For greater clarity and understanding of the object of the present invention, it has been illustrated in several figures, in which it has been represented in one of the preferred embodiments, all by way of example, where:

Figure 1 is an electrical diagram of the equipment used with the method object of the present invention;

Figures 2a and 2b are schematic images.

Figure 3 represents the graphs a-e showing the results obtained by the method of the present invention.

DETAILED DESCRIPTION OF THE EXAMPLE OF EMBODIMENT Referring to figure 1, the equipment consists of:

a) A first coil system to determine the properties of hysteresis cycles performed at 50 Hz (by traditional methods) with a primary or inductor winding and a secondary or induced winding arranged the second within the first in a co-linear fashion. The sample is placed inside this second winding (coil systems shown in Fig. 1).

b) A second coil system to determine the high frequency magnetic permeability (50 to 5000 kHz, for example) by traditional methods with a primary or inductor winding and a secondary or induced winding arranged the second one inside the first one in a co-linear way, as in case (a), but with different electrical characteristics, optimized for this type of measurement. The sample is placed inside this second winding (the coil system is not shown in Fig. 1 for reasons of clarity of the graph, but it is somewhat analogous to the system (a)).

c) A sample fastening system in the form of a tape, which provides the electrical contacts for annealing by Joule effect and also provides (or not) the mechanical stresses for annealing under stresses (shown in Fig. 2).

d) A current source for annealing (100 or 200 W of power) e) A current and / or voltage amplifier for the generation of the magnetic field.

f) A hardware composed of a data acquisition card. g) A software based on the Labview architecture of virtual instrumentation.

The two sets of coils (to perform hysteresis cycles and to determine the magnetic permeability) are placed vertically, the sample is passed about 12 cm long (the sample must be in the form of a tape or thread) through the inside the secondary coils and the sample is held tightly at both ends with electrical contactors (electrodes) (Fig. 2). To prevent the weight of the electrodes from affecting either the measurements or the domain structure during heat treatments (in samples sensitive to mechanical stresses), the lower electrode is placed on one end of a lever scale and its weight is compensated with weights at the other end (Fig. 2a).

If, on the contrary, it is necessary to apply a tension to study its effect, the weights are placed on the lower electrode (Fig. 2b.) - If it is required to perform treatments with magnetic field applied in a co-linear way to the tape, it can be used the primary coil to generate that field. If a cross-sectional field is required to the belt, an additional coil (of Helmholtz, for example) can easily be implemented for this. These two types of experiments, with applied stresses and applied magnetic field, are very common in these types of materials (eg [1], [2]).

The principle of operation consists in passing a current through the sample for a few seconds (approx. 6 seconds). During that time, the sample becomes heated at a temperature that will depend on the current supplied; at this temperature the electrical resistance, the coercive field, the saturation magnetization and the magnetic permeability are measured. Next, the sample is allowed to stand at room temperature to re-take the measurements of these four quantities. The process is repeated at a higher current (higher temperature) and the events are recorded.

Referring to Figure 3, the results obtained in a heating cycle of an initially amorphous tape of chemical composition of Fe ₇ 3 YES 16.5 B Nb ₃ Cuj, of dimensions 12 cm long and cross section of 0, are observed. 5 x 0.026 mm2. The heating cycle began by applying a current of 0.2 A. It was previously verified that, with this current value, it does not produce any structural change in the sample.

From 0.2 A the current was raised to 0.22 in four stages of 0.05A each

(ie: 0.205, 0.21, 0.215 and 0.22 A) with a duration of 1.5 s at each stage. Next, the current was lowered to 0 A. In each of the stages, including that of 0 A, the values of: Saturation Imanation (Ms), Coercive Field (He, 50Hz), Magnetic Permeability (ur, 100kHz) were determined ) and electrical resistance (R). Then, once the initial temperature of the system was reached, it was continued towards a second point until 0.24 A in four stages (previous idem) and then at 0 A (previous idem). In this way, the curves of Fig. 3 could be constructed, where only the values obtained in the maximum current and 0 current stages were placed in each step (due to the clarity of the figures, understanding that the first stages they are transitory, and that would not provide more information) but all the information is recorded in individual files for later analysis if desired.

Properties obtained:

1. Ms at high temperature, Ms ^Temp , in Graf. (to)

2. Ms at room temperature, Ms ^Amb , in Graf. (to)

3. He at high temperature, Hc ^Temp , in Graph (b)

4. He at room temperature, Hc ^Amb , in Graf. (C)

5. R at high temperature, R ^Tem P _{5 e} n Graph. (d)

6. R at room temperature, R ^m , in Graf. (d)

7. _μ - at high temperature, Temp, in Graf (e)

Amb

8. μτ at room temperature. ', in Graf. (and)

From the analysis of these curves you can see that: During the first stage there are no significant structural changes or structural relaxation until the annealing current value of 0.5 A, which is detectable by all the measured properties. From that annealing current value, a structural relaxation can be detected, which is mainly detected by the measures of ^ ^m , and to a much lesser extent, by the Hc ^Amb . Structural relaxation comprises regions 2 and 3 (R2 and R3, respectively). These two regions are divided by the start of the magnetic disorder clearly indicated by the Curie Temperature (T _c l) with Ms ^Temp in the graph. (a), and the fall of the ur ^Temp on the Graf (e). It is interesting to note that the other six properties measured by the equipment do not clearly detect the beginning of structural relaxation. Hence the importance of having the ability to measure all these properties. In the course of evolution, this fact, that some properties detect some change and others do not, will be repeated continuously.

Stage II, nanocrystallization (R4). This stage is marked by the (nano) crystallization of part of the material that is clearly observed by the fall of the R ^Amb because the crystalline material is a better electrical conductor than the amorphous. In the R ^Temp it is also possible to notice a change in the slope precisely because it is no longer the same amorphous material but it is another material (nanocrystallized). The consequences of this structural change in the magnetic properties are clearly observed in the Hc ^Amb that reaches its minimum value, in the μτ ^^ that reaches its maximum value. This is the stage of better conditions for a heat treatment.

Stage III of massive crystallization (R5). From approximately 0.9A of heat treatment current, the material begins a massive crystallization that loses soft magnetic properties. This is confirmed by the increase in Hc ^Amb and the decrease of ^ ^m . Stage IV, return monitoring. What can be observed that during the reverse of the heat treatment, the material continues some structural changes initiated at the end of the cycle (Le., At 1A currents) since the Ms ^Amb shows an increase in its return and the Ms ^Temp lets see clearly the peak of a new magnetic phase towards 0.83 A, which did not exist in the first heat treatment (the first leg). In addition, the temperature of Curie T _c 2 of the amorphous material is still observed, which indicates that the crystallization has not been total.

From the above, it turns out that with a sample we have been able to obtain a large amount of data about its structural and magnetic evolution, that otherwise we would have had to use at least three devices, using different samples and without knowing the data at room temperature.

The steps necessary to carry out the experiment described in the present invention are described below.

1) A piece of tape (or child) of the material to be tested is cut with a length of approximately 12 cm.

2) The tape is placed inside the carrier tube of the two sets of reels as shown in figure 2.

3) The electrodes are each placed near the ends of the tape (figure 2)

4) A continuity test is performed (test incorporated in the software), to ensure that current passes through the electrodes and through the sample.

5) The lower electrode is placed in supports as a scale saucer if it is intended to perform the test without induced mechanical stresses. If stresses were to be induced, the corresponding weights for the desired mechanical tension are added to the electrode.

6) The data is placed in the software to perform the desired heat treatment and the experiment begins.

Possible commercial uses and applications:

a) The equipment is used to perform magnetic response studies of amorphous and nanocrystalline materials based on annealing (thermal treatments) carried out by the Joule heating technique. In this way, the correct heat treatment can be determined to obtain the optimum magnetic characteristic desired.

b) The equipment is able to determine the magnetic properties either at room temperature or during annealing (temperatures> 1000 ° C) for short periods of time (enough for the material to stabilize in temperature and take the measurements).

c) The magnetic properties that can be determined are: Saturation Magnetization, Coercive Field and frequency permeability. Work is being done to improve the magnetic losses. These measurements could be carried out at low or high frequencies, depending on the instruments used for the generation and acquisition of data and the coil set used. At present, the saturation magnetization and the coercive field is being determined at a frequency of 50 Hz and the permeability at 100 kHz, both frequencies chosen by the characteristics of the materials we are testing.

d) It has the possibility of annealing with the application of a magnetic field (in the case of the prototype, the field is only applied co-linearly with the tape, but a second coil can be arranged transversely, for example, with a coil of Helmholtz) or with mechanical tensions. These studies are frequent. for this type of materials since they change their magnetic properties for their commercial application.

e) In addition to the magnetic properties, the equipment determines the electrical resistance of the sample based on annealing, at high temperature and at room temperature.

f) By combining the information of magnetic and electrical responses, interesting studies about structural evolution (structural relaxations, and crystallization, Curie temperature) can be carried out, very interesting data for research laboratories.

References cited in this description

[1] T. Jagielinski, Flash annealing of amorphous alloys, IEEE Trans. Magn. 19 (1983) 1925-1927. doi: 10.1109 / TMAG.1983.1062629.

[2 P. Rougier, R. Krishnan, Stability studies in Fe-Ni based amorphous ribbons: Some refinement, IEEE Trans. Magn. 23 (1987) 2134-2135. doi: 10.1109 / TMAG.1987.1065626.

[3] C. Djega-Mariadassou, P. Rougier, J.L. Dormann, H. Kadiri, A. Berrada, Joule heating method coupled with Móssbauer spectroscopy for the study of the crystallization of amorphous ribbons, Hyperfine Interact. 45 (1989) 343-350. doi: 10.1007 / BF02405898.

[4JF.CS da Silva, EF Ferrari, M. Knobel, IL Torriani, DR dos Santos, Controlling Fe nanocrystallization in amorphous Fe [sub 86] Zr [sub 7] Cu [sub l] B [sub 6] by linear varying current Joule heating, Appl. Phys. Lett. 77 (2000) 1375. doi: 10.1063 / l.1290049. [5] JA Moya, V. Cremaschi, FCS Silva, M. Knobel, H. Sirkin, Infuence of the heat treatment method on magnetic and mechanical properties of the Fe73.5Sil3.5B9Nb3Cul alloy, J. Magn. Magn. Mater. 226-230 (2001) 1522} 1523. doi: http: //dx.doi.org/10.1016/S0304-8853 (00) 00945-8.

[6] P. Kwapulinski, J. Rasek, Z. Stoklosa, G. Haneczok, Optimization of soft magnetic properties in Fe-Cu-X-Sil3B9 (X = Cr, Mo, Zr) amorphous alloys, J. Magn. Magn. Mater. 234 (2001) 218-226. doi: 10.1016 / S0304-8853 (01) 00349-3.

[7] N. Mitrovic, S. Roth, S. Djukic, J. Eckert, Magnetic Softening of Metallic Glasses by Current Annealing Technique, in: B. Idzikowski, P. Svec, M. Miglierini (Eds.), Prop. Appl. Nanocrystalline Alloys Amorph. Precursors, Springer-Verlag, Berlin / Heidelberg, 2005: pp. 331-344. http://link.springer.com/10.1007/l-4020-2965-9_30 (accessed September 24, 2015).

[8] F. Mazaleyrat, J.C. Faugiéres, J.F. Rialland, Thermomagnetic study of Finemet type nanocrystalline alloy by in situ hysteresis measurements, J. Magn. Magn. Mater. 159 (1996) L33-L38. doi: 10.1016 / 0304-8853 (96) 00372-l.

Claims

CLAIMS Having thus specifically described and determined the nature of the present invention and the manner in which it is to be carried out, it is claimed to claim as exclusive property and right:

1. A device for the study of the evolution of the magnetic and structural properties of amorphous and nanocrystalline soft magnetic materials, the device being characterized in that it comprises at least a first set of coils for the determination of hysteresis cycles, at least a second set of coils for the determination of magnetic permeability, an arrangement for holding the sample in the form of a tape, so that it can remain with or without mechanical stresses, an energy source for annealing, a current amplifier and / or voltage, associated hardware and software.

2. The device according to claim 1, characterized in that said coil set determines the properties of hysteresis cycles performed at 50 Hz (by traditional methods) with a primary or inductor winding and a secondary or induced winding arranged the second within the first co-linear

3. The device according to claim 1, characterized in that said according to set of coils are intended to determine the high frequency magnetic permeability (50 to 5000 kHz, for example) by traditional methods with a primary or inductor winding and another secondary or induced the second arranged inside the first one in a co-linear way but with different electrical characteristics, optimized for this type of measurement.

4. The device according to claim 1, characterized in that it is a current device with a power between 100 and 200 watts.

5. The device according to claim 1, characterized in said current and / or voltage amplifier is defined for the generation of the magnetic field.

6. The device according to claim 1, characterized in that said hardware is composed of a data acquisition card.

7. The device according to claim 1, characterized in that said software is based on the Labview virtual instrumentation architecture.

8. A method for studying the evolution of the magnetic and structural properties of amorphous and nanocrystalline soft magnetic materials, using the device of claim 1, characterized in that the sample is placed vertically within the second set of coils.

9. The method according to claim 1, characterized in that it comprises the steps of:

a) Cut a piece of tape (or child) of the material to be tested with a length of approximately 12 cm.

b) Place the tape inside the carrier tube of the two sets of reels. c) Place the electrodes each near the ends of the tape d) Perform a continuity test (test incorporated in the software), to ensure that current passes through the electrodes and the sample.

e) Place the lower electrode on supports as a scale saucer if it is intended to perform the test without induced mechanical stresses. If stresses were to be induced, the corresponding weights for the desired mechanical tension are added to the electrode.

f) The data is placed in the software to perform the desired heat treatment and the experiment begins.