HK1019345B - Metallic glass alloys for mechanically resonant marker surveillance systems - Google Patents

Description

Glassy metal alloy for mechanical resonance marker surveillance systems

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a continuation of the invention section filed 4/13 of 1995, U.S. application serial No.08/421,094, entitled glassy metal alloy for use in a mechanical resonance marker monitoring system.

Background

1. Field of the invention

The present invention relates to glassy metal alloys; and more particularly to glassy metal alloys suitable for use as mechanical resonance markers in article surveillance systems.

2. Description of the prior art

There are many article surveillance systems available on the market that can help identify different living and non-living beings and/or ensure their safety. The purpose of using such a system is, for example, to identify personnel to control their entry into restricted areas and to ensure that merchandise is not stolen.

One of the basic components of all surveillance systems is a sensor or "tag" which is attached to the object being monitored. Other components of the system include a transmitter and a receiver suitably arranged in an "interrogation" zone. When an object enters the interrogation zone with the tag, the functional component of the tag responds to a signal from the transmitter, which response is detected by the receiver. The signals contained in the response signals are then processed into actions suitable for the application: deny entry, initiate an alarm, etc.

Several different types of markers have been invented and used. One type of functional part comprises an antenna and a diode or an antenna and several capacitors to form a resonant loop. When the antenna-diode marker is placed in the electromagnetic field emitted by the interrogation device, it generates harmonics in the receiving antenna having the interrogation frequency. Upon detection of a change in harmonic or signal strength, the presence of a marker is declared. However, such marker identification systems are less reliable because of the wider bandwidth of the simple resonant circuit. Furthermore, because such a marker must be removed after identification, it is not desirable for an anti-theft system.

Another type of marker comprises a first elongated element made of ferromagnetic material of high magnetic permeability and adjacent to at least one second element of a ferromagnetic material having a higher coercivity than the material of the first element. When such a marker is subjected to electromagnetic radiation at an interrogation frequency, it generates a resonant wave having the interrogation frequency in accordance with the nonlinear characteristics of the marker. Such a resonance wave detected in the receiving coil indicates the presence of the marker. The deactivation of the marker may be accomplished by changing the magnetization state of the second element, which may be easily accomplished, for example, by passing the marker through a dc magnetic field. Harmonic marker systems are advantageous over the previously described radio frequency resonance systems because it improves the reliability of marker identification and simplifies the passivation method. However, there are two main problems with this type of system: one is the difficulty in detecting the marker signal at long distances. The amplitude of the harmonics produced by the marker is much smaller than the amplitude of the interrogation signal, so that the width of the detection channel is limited to within about 91.5 cm. Another problem is the difficulty in discerning the marker signal from spurious signals generated by other ferromagnetic objects, such as tape tabs, recording heads, steel clips, and the like.

A monitoring system with a detection state and incorporating the fundamental mechanical resonance frequency of the marker material is a very excellent system because it combines high detection sensitivity, high operational reliability and low cost. Examples of such systems are disclosed in U.S. patent nos.4,510,489 and 4,510,490 (hereinafter the '480 and' 490 patents).

The marker of such a system is a strip or strips of ferromagnetic material of known length encapsulated with a more magnetic ferromagnetic body (material with a higher coercivity) which provides a bias field to create maximum magnetic and mechanical coupling. Ferromagnetic marker materials are preferably glassy metal alloy ribbon because of the high efficiency of magnetic and mechanical coupling in such alloys. The mechanical resonance frequency of the marker material is essentially determined by the alloy strip length and the bias field strength. When the marker receives an interrogation signal tuned to a resonant frequency, the marker material responds to a large signal field, which is detected by the receiver. This large signal field is due in part to the increased permeability of the marker material at the resonant frequency. Various marker configurations and systems for use in interrogation and detection using the principles described above are taught in the '489 and' 490 patents.

In one particularly useful system, the marker material is excited to oscillate by a burst or short burst of a signal having its resonant frequency generated by a transmitter. When the excitation pulse ends, the marker material will undergo a decaying oscillation with a resonant frequency, i.e. the marker material "ends up" with the end of the excitation pulse. The receiver "hears" this response signal during the gradual end period. In this design, the monitoring system is not affected by other different transmitted signals or power line interference sources, thereby substantially eliminating potential false alarms.

A wide range of alloys are available for use with different detection system marker materials, and these alloys are patented in the '480 and' 490 patents. Other glassy metal alloys having high magnetic permeability are disclosed in U.S. patent 4,152,144.

One of the major problems with electronic product surveillance systems is the tendency of mechanical resonance based surveillance system markers to accidentally trigger surveillance systems employing alternate technologies, such as the resonant marker systems described above: the non-linear magnetic response of the marker is strong enough to produce resonance in the alternating system, thereby accidentally producing a false response, or "false" alarm. The importance of avoiding interference or "contamination" between different monitoring systems is evident. Therefore, there is a need in the art for a resonant marker that can be detected in a highly reliable manner without contaminating systems based on alternate techniques such as harmonic re-radiation.

Summary of The Invention

The present invention provides magnetic alloys, at least 70% of which are glassy and the magnetic properties of which are enhanced by annealing, characterized in that they exhibit a relatively linear magnetic response over a frequency range in which a harmonic marker magnetic field acts. The alloy may be cast into a ribbon form by rapid solidification techniques or otherwise formed into a marker, the magnetic and mechanical properties of which are particularly suited for use in marker-based magneto-mechanical surveillance systems. In general, the composition of the glassy metal alloys of the present invention consists essentially of the formula Fe_aCo_bNi_cM_dB_eSi_fC_gWherein M is selected from molybdenum, chromium, and manganese, "a", "b", "c", "d", "e", "f", and "g" are atomic percentages, "a" is about 30 to 45, "b" is about 4 to 40, "c" is about 5 to 45, "d" is about 0 to 3, "e" is about 10 to 25, "f" is about 0 to 15, and "g" is about 0 to 2. When the mechanical resonance frequency is in the range of about 48 to about 66KHz, these alloy strips not only show that the slope of the resonance frequency versus bias field curve of the conventional mechanical resonance marker approaches or exceeds about 400Hz/Oe, but also the relative linear magnetization behavior can be continued until the applied field reaches 8Oe or higher. In addition, markers made from the alloys of the present invention have a voltage amplitude that is comparable to or higher than the existing resonant marker voltage amplitude detected by the receiver coil in a typical resonant marker system. These features ensure avoidance ofAvoiding the mutual interference between systems based on mechanical resonance and harmonic reradiation.

The glassy metals of the present invention are particularly useful as active elements for markers for article surveillance systems that are excited and detected using magnetomechanical resonance as described above. Other uses are: for use in sensors that utilize magneto-mechanical action and its associated effects, and in magnetic elements that require high magnetic permeability.

Brief Description of Drawings

The present invention will be more fully understood and further advantages will become apparent from the following detailed description of the preferred embodiments of the invention and the accompanying drawings, in which:

FIG. 1(a) is a schematic diagram of a magnetization curve of a conventional resonant marker along a length direction, wherein B is magnetic induction and H is an applied magnetic field;

FIG. 1(B) is a schematic view of the magnetization curve of the marker of the present invention along the length direction, Ha being the magnetic field at B saturation;

fig. 2 is a schematic diagram of a signal waveform measured at a receive coil depicting the excitation of mechanical resonance, ending at time t0, followed by a gradual end period, where V0 and V1 are the signal amplitudes in the receive coil at t-t 0 and t-t 1 (1 millisecond after t 0), respectively;

FIG. 3 is a schematic representation of the mechanical resonance frequency fr and the response signal V1 detected by the receiving coil at 1 millisecond after the end of the excitation AC field as a function of the bias field Hb, where H_b1And H_b2The bias field at the maximum V1 and at the minimum fr, respectively.

Detailed description of the preferred embodiments

In accordance with the present invention, a magnetic glassy metal alloy is provided which is characterized by a relatively linear magnetic response to a frequency range of operation of a magnetic field of a harmonic marker system. All the characteristics of the alloyAre suitable for the needs of markers for monitoring systems based on magneto-mechanical effects. In general, the composition of the glassy metal alloys of the present invention consists essentially of the formula Fe_aCo_bNi_cM_dB_eSi_fC_gWherein M is selected from molybdenum, chromium, and manganese, "a", "b", "c", "d", "e", "f", and "g" are atomic percentages, "a" is about 30 to 45, "b" is about 4 to 40, "c" is about 5 to 45, "d" is about 0 to 3, "e" is about 10 to 25, "f" is about 0 to 15, and "g" is about 0 to 2. The purity of the above components is the purity that is used in common commercial practice. These alloy strips are annealed at a high temperature for a given time under a magnetic field across the width of the strip. The temperature of the tape is below its crystallization temperature and the heat treatment is required to have sufficient cutting plasticity. The field strength in the anneal should saturate the magnetization of the ribbon in the field direction. The annealing time is determined according to the annealing temperature, and typically ranges from several minutes to several hours. For commercial products, a continuous disc lehr is preferred. In this case, the belt conveying speed may be set to about 0.5 to 12 meters per minute. The annealed ribbon has a length of about 38mm, exhibits a relatively linear magnetic response to an applied magnetic field of 8Oe or greater parallel to the length of the marker, and exhibits a mechanical resonance at a frequency of between 48KHz and 66 KHz. The linear magnetic response region is expanded to 8Oe, enough to avoid starting some harmonic marker systems. In some more severe cases, the linear magnetic response region can be extended beyond 8Oe by changing the composition of the alloys of the present invention. After annealing, the tape having a tape length of less than or greater than 38mm exhibits a mechanical resonance frequency in the range of greater than or less than 48 to 66 KHz.

A band having a mechanical resonance frequency of 48 to 66KHz is preferable. Such a strip is short enough for disposable marker materials. In addition, the resonance signals of such a band can be well distinguished from audio and commercial radio frequencies.

Most glassy metal alloys outside the scope of the present invention generally exhibit a non-linear magnetic response below the 8Oe level, or Ha level close to the operating magnetic field excitation strength of an article detection system using harmonic markers. Resonant markers containing such materials can inadvertently activate and contaminate many harmonic re-radiation type detection systems.

There are some glassy metal alloys outside the scope of the present invention that do exhibit a linear magnetic response in an acceptable magnetic field range. However, these alloys contain too much cobalt or molybdenum or chromium, resulting in increased raw material costs and/or reduced belt castability due to the high melting point of the elements molybdenum or chromium. The alloys of the invention are excellent and they combine the following advantages: the linear magnetic response is enlarged, the mechanical resonance performance is improved, the belt castability is good and the production economy of usable belts is improved.

The marker made of the alloy of the invention can avoid the interference among different systems, and can generate larger signal amplitude in a receiving coil than the traditional mechanical resonance marker. This makes it possible to reduce the size of the marker or increase the width of the detection channel, both of which are required by the article surveillance system.

Examples of glassy metal alloys of the present invention include:

Fe₄₀Co₃₄Ni₈B₁₃Si₅，Fe₄₀Co₃₀Ni₁₂B₁₃Si₅，Fe₄₀Co₂₆Ni₁₆B₁₃Si₅，

Fe₄₀Co₂₂Ni₂₀B₁₃Si₅，Fe₄₀Co₂₀Ni₂₂B₁₃Si₅，Fe₄₀Co₁₈Ni₂₄B₁₃Si₅，

Fe₃₅Co₁₈Ni₂₉B₁₃Si₅，Fe₃₂Co₁₈Ni₃₂B₁₃Si₅，Fe₄₀Co₁₆Ni₂₆B₁₃Si₅，

Fe₄₀Co₁₄Ni₂₈B₁₃Si₅，Fe₄₀Co₁₄Ni₂₈B₁₆Si₂，Fe₄₀Co₁₄Ni₂₈B₁₁Si₇，

Fe₄₀Co₁₄Ni₂₈B₁₃Si3C₂，Fe₃₈Co₁₄Ni₃₀B₁₃Si₅，Fe₃₆Co₁₄Ni₃₂B₁₃Si₅，

Fe₃₄Co₁₄Ni₃₄B₁₃Si₅，Fe₃₀Co₁₄Ni₃₈B₁₃Si₅，Fe₄₂Co₁₄Ni₂₆B₁₃Si₅，

Fe₄₄Co₁₄Ni₂₄B₁₃Si₅，Fe₄₀Co₁₄Ni₂₇Mo₁B₁₃Si₅，Fe₄₀Co₁₄Ni₂₅Mo₃B₁₃Si₅，

Fe₄₀Co₁₄Ni₂₇Cr₁B₁₃Si₅，Fe₄₀Co₁₄Ni₂₅Cr₃B₁₃Si₅，

Fe₄₀Co₁₄Ni₂₅Mo₁B₁₃Si₅C₂，Fe₄₀Co₁₂Ni₃₀B₁₃Si₅，

Fe₃₈Co₁₂Ni₃₂B_13-Si₅，Fe₄₂Co₁₂Ni₃₀B₁₃Si₅，-Fe₄₀Co₁₂Ni₂₆B₁₇Si₅，

Fe₄₀Co₁₂Ni₂₈B₁₅Si₅，Fe₄₀Co₁₀Ni₃₂B₁₃Si₅，Fe₄₂Co₁₀Ni₃₀B₁₃Si₅，

Fe₄₄Co₁₀Ni₂₈B₁₃Si₅，Fe₄₀Co₁₀Ni₃₁Mo₁B₁₃Si₅，Fe₄₀Co₁₀Ni₃₁Cr₁B₁₃Si₅，

Fe₄₀Co₁₀Ni₃₁Mn₁B₁₃Si₅，Fe40Co₁₀Ni₂₉Mn₃B₁₃Si₅，

Fe₄₀Co₁₀Ni₃₀B₁₃Si₅C₂，Fe₄₀Co₈Ni₃₈B₁₃Si₅，Fe₄₀Co₆Ni₃₆B₁₃Si₅，and

Fe₄₀Co₄Ni₃₈B₁₃Si₅，

where the subscripts are atomic percent.

FIG. 1(a) shows the magnetization behavior of a conventional mechanical resonance marker, which is characterized by a B-H curve, where B is the magnetic induction and H is the applied magnetic field. The entire B-H curve is cut by the non-linear hysteresis loop in the low magnetic field region. This non-linear characteristic of the marker results in higher order harmonic generation that may activate some harmonic marker systems, causing interference between different article surveillance systems.

The linear magnetic response is illustrated in fig. 1 (b). When the marker is magnetized by an externally applied magnetic field H along the length direction, magnetic induction B is generated in the marker. This magnetic response can remain relatively linear until Ha, beyond which the marker magnetically saturates. The value of Ha depends on the actual size of the marker and its magnetic anisotropy field. In order to prevent the resonant marker from accidentally activating a monitoring system based on harmonic re-radiation, Ha should be above the field strength region of the harmonic marker system.

The marker material is subjected to a short pulse train of an excitation signal with a constant amplitude, called excitation pulse, whose frequency is adjusted to the mechanical resonance frequency of the marker material. As the curve reaches V0 in fig. 2, the marker material responds to the excitation pulse and generates an output signal in the receive coil. At time t0, the excitation ends and the marker begins to gradually end, i.e., decrease from V0 to zero over time in the output signal. At time t1, i.e., 1 millisecond after the end of the excitation, the output signal is measured and represented by V1. Thus V1/V0 is a measure of the gradual end. The waveform of this signal is typically a sine wave, although the principle of operation of the monitoring system does not rely on the shape of the wave comprising the excitation pulse. The marker material resonates under this excitation.

The physical principles of this resonance can be summarized as follows: when a ferromagnetic material is placed in an excitation magnetic field, its length changes. This change in material from the original length is called magnetostriction and is denoted by the symbol λ. If the material elongates parallel to the excitation field, the lambda sign is positive.

When a strip material having positive magnetostriction properties is placed in a sinusoidal applied magnetic field along its length, the length of the strip will undergo periodic changes, i.e. the strip will be forced to oscillate. This externally applied magnetic field may be generated by a solenoid with a sinusoidally varying current. Mechanical resonance results when the half wavelength of the oscillation wave of the band matches the length of the band. The resonance frequency fr is given by the following relation:

fr＝(1/2L)(E/D)^0.5where L is the ribbon length, E is the Young's modulus of the ribbon, and D is the density of the ribbon.

The magnetostrictive effect of ferromagnetic materials is only observed when the magnetization of the material proceeds in a rotating magnetization. When the magnetization process is performed during the motion of the domain wall, the magnetostrictive effect is not observed. Since the magnetic anisotropy of the marker made of the alloy of the present invention is excited in the annealing of the magnetic field across the width of the marker, a direct magnetic field called a bias field is applied to the length of the marker,to enhance the magneto-mechanical response effect of the marker material. It is also well understood in the art that the use of a biasing magnetic field can change the effective value of the young's modulus E of a ferromagnetic material, so that appropriate selection of the strength of the biasing magnetic field can change the mechanical resonant frequency of the material. This can be further explained by the schematic diagram 3: the resonance frequency fr decreases with the bias magnetic field Hb, at H_b2Minimum value of Fangda (fr)_min. Signal response value V1 detected in the receiving coil at t1 as a function of H_bAnd is increased at H_b1Up to a maximum value V_m. Slope dfr/dH in the vicinity of the applied bias field_bIs an important quantity because it is related to the sensitivity of the monitoring system.

In summary, when a strip of ferromagnetic material having positive magnetostriction properties is subjected to an exciting alternating magnetic field having a direct current bias field, it will oscillate at the frequency of the exciting alternating field, and when this frequency coincides with the material mechanical resonance frequency fr, the strip will resonate and produce an enhanced response signal amplitude. In practice, the bias field is provided by a ferromagnetic body having a higher coercivity than the marker material in the "marker assembly".

Table I shows the glass state of Fe₄₀Ni₃₈Mo₄B₁₈Typical V of traditional mechanical resonance marker made_m、H_b1、(fr)_minAnd H_b2The value is obtained. Low H_b2Value and in H_b2The non-linearity of the B-H behavior below the value makes markers made from such alloys prone to accidental activation of some harmonic marker systems, resulting in interference between article surveillance systems based on mechanical resonance and harmonic re-radiation.

TABLE I

From glassy state Fe₄₀Ni₃₈Mo₄B₁₈Typical V of traditional mechanical resonance marker made_m、H_b1、(fr)_minAnd H_b2The value is obtained. The band has a length of 38.1mm and a mechanical resonance frequency in the range of about 57 to 60 KHz.

V_m(mV) H_b1(O_e) (fr)_min(KHz) H_b2(O_e)

150-250 4-6 57-58 5-7

Table II shows typical H of alloys outside the scope of this patent_a、V_m、H_b1、(fr)_min、H_b2And dfr/dH_bThe value is obtained. The field annealing was done in a continuous disk furnace with a 12.7mm strip width and a strip speed from about 0.6m/min to about 1.2 m/min.

TABLE II

Alloy H outside the scope of this patent_a、V_m、H_b1、(fr)_min、H_b2And H_b＝6O_eValue of dfr/dhb. The field annealing is carried out in a continuous disk furnace with a ribbon velocity of from about 0.6m/min to about 1.2m/min, 1.4KO_ePerpendicular to the length direction of the strip.

Component H_a(Oe) V_m(mV) H_b1(Oe) (f_c)_min(kHz) H_b2(Oe) df_r/dH_b(Hz/Oe)

A.Co₄₂Fe₄₀B₁₃Si₅ 22 400 7.0 49.7 15.2 700

B.Co₃₈Fe₄₀Ni₄B₁₃Si₅ 20 420 9.3 53.8 16.4 500

C.Co₂Fe₄₀Ni₄₀B₁₃Si₃ 10 400 3.0 50.2 6.8 2.080

D.Co₁₀Fe₄₀Ni₂₇Mn₅B₁₃Si₅ 7.5 400 2.7 50.5 6.8 2.300

Although alloys a and B exhibit linear magnetic responses to an acceptable magnetic field range, they contain large amounts of cobalt, resulting in an increase in raw material prices. Alloys C and D have a low H_b1Values and high values of dfr/dHb, both of which are undesirable from the standpoint of operation of the resonant marker system.

Examples

Example 1: Fe-Co-Ni-B-Si glassy metal

1. Sample preparation

The samples 1 through 29 shown in tables III and IV are Fe-Co-Ni-B-Si series glassy metal alloys that are rapidly quenched from the molten state in accordance with Narasimohan, U.S. Pat. No.4,142,571, the contents of which are incorporated herein by reference. All casting was carried out in inert gas with 100g of melt. The resulting tapes are typically 25 μm thick and about 12.7mm wide using Cu-K_αNo apparent crystallinity in the bands was determined by radiation X-ray diffraction and differential scanning calorimetry. Each alloy is at least 70% glassy, and in many instances, more than 90% glassy. These glassy metal alloy ribbons have high strength, good gloss, high hardness, and good plasticity.

The tape was cut into small pieces for magnetization, magnetostriction, curie point and crystallization temperature and density measurements. To characterize the magneto-mechanical resonance, the strip was cut to a length of about 38.1mm and placed in a magnetic field across the width of the strip for thermal treatment. The magnetic field strength was 1.1KOe or 1.4KOe and varied between 75 and 90 degrees from the tape length direction. Some belts are heat treated under the condition of applying stress along the belt direction, and the stress is 0-7.2 Kg/mm²In the meantime. The speed of the belt in the continuous pan annealing furnace varied between 0.5 meters per minute and 12 meters per minute.

2. Magnetic and thermal Properties

Table III shows the saturation induction (Bs), saturation magnetostriction (. lamda.s), and crystallization temperature (Tc) of the alloys. The magnetization is measured by a vibrating sample magnetometer and gives a saturated magnetization value in emu/g, which can be converted to saturated magnetic induction using density data. The saturation magnetostriction can be measured by the strain gauge method and has a unit of 10^-6Or ppm. The curie point and crystallization temperature were measured by the electric induction method and a differential scanning calorimeter, respectively.

TABLE III

Magnetic and thermal properties of Fe-Co-Ni-B-Si glassy alloys. In the alloy, curie temperatures of No.22(θ f is 447 ℃), No.27(θ f is 430 ℃), No.28(θ f is 400 ℃) and No.29(θ f is 417 ℃) can be determined because their curie points are lower than the primary crystallization temperature (Tc).

No component B_s(Tesla) λ_s(ppm) T_c(℃)

Fe Co Ni B Si

1 40 34 8 13 5 1.46 23 456

2 40 30 12 13 5 1.42 22 455

3 40 26 16 13 5 1.38 22 450

4 40 22 20 13 5 1.32 20 458

5 40 20 22 13 5 1.28 19 452

6 40 18 24 13 5 1.25 20 449

7 35 18 29 13 5 1.17 17 441

8 32 18 32 13 5 1.07 13 435

9 40 16 26 13 5 1.21 18 448

10 40 14 28 13 5 1.22 19 444

11 40 14 28 16 2 1.25 19 441

12 40 14 28 11 7 1.20 15 444

13 38 14 30 13 5 1.19 18 441

14 36 14 32 13 5 1.14 17 437

15 34 14 34 13 5 1.09 17 434

16 30 14 38 13 5 1.00 10 426

17 42 14 26 13 5 1.27 21 448

18 44 14 24 13 5 1.31 21 453

19 40 12 30 13 5 1.20 18 442

20 38 12 32 13 5 1.14 18 440

21 42 12 30 13 3 1.29 21 415

22 40 12 26 17 5 1.12 17 498

23 40 12 28 15 5 1.20 19 480

24 40 10 32 13 5 1.16 17 439

25 42 10 30 13 5 1.15 19 443

26 44 10 28 13 5 1.25 20 446

27 40 8 34 13 5 1.11 17 437

28 40 6 36 13 5 1.12 17 433

29 40 4 38 13 5 1.09 17 430

Each marker material size was about 38.1mm x 12.7mm x 20 μm, their Ha values were measured with a conventional B-H hysteresis loop indicator and then placed in a 221 turn sensing coil. An alternating magnetic field is applied in the longitudinal direction of each alloy marker, with a direct magnetic bias field having a strength of from 0 to about 20 Oe. The sensing coil detects the magneto-mechanical response of the alloy marker to the ac excitation. The marker material mechanical resonant frequencies are between about 48-66 KHz. The magneto-mechanical response values for the alloys listed in Table III were measured and are listed in Table IV.

TABLE IV

Ha, Vm, H of the alloys in Table III_b1、(fr)_min、H_b2And H_bThe heat treatment of the alloy was carried out in a continuous disk lehr at a temperature of 380 c, a belt speed of about 1.2m/min and heating at 415 c for 30 minutes (indicated by asterisks) at a value of dfr/dHb of 6 Oe. The annealing field was about 1.4KOe, perpendicular to the ribbon length direction.

Alloy number H_a(Oe) V_m(mV) H_b1(Oe) (f_r)_min(kHz) H_b2(Oe) df_r/dH_b(Hz/Oe)

1 21 415 10.3 54.2 16.5 460

2 20 370 10.7 54.2 16.0 560

3 20 370 10.0 53.8 16.5 430

4^* 20 250 10.5 49.8 17.7 450

4 18 330 8.0 53.6 14.2 590

5 17 270 9.0 52.0 14.5 710

6 17 340 7.8 53.4 14.2 620

7 16 300 8.6 53.5 14.3 550

8 15 380 8.0 54.1 13.0 580

9 16 450 7.8 51.3 14.2 880

10^* 17 390 8.9 49.3 15.9 550

10 16 390 7.0 52.3 13.4 810

11 15 350 8.0 52.3 13.9 750

12 14 350 7.0 52.5 12.4 830

13 14 400 7.3 52.5 13.1 780

14 13 330 6.5 54.2 12.6 670

15 13 270 6.2 53.0 11.5 820

16 10 230 5.0 56.0 9.3 1430

17 15 415 7.2 51.2 14.3 740

18 15 350 7.7 50.4 12.9 1080

19 14 440 6.5 50.6 11.6 960

20 14 330 6.6 52.9 11.3 900

21 19 325 9.3 53.9 14.8 490

22 9 260 3.5 55.8 8.0 1700

23 11 310 5.4 52.2 10.5 1380

24^* 15 220 8.2 48.5 13.7 740

24 14 410 7.5 51.8 13.5 800

25 13 420 6.2 49.5 12.2 1270

26 14 400 6.0 50.2 12.8 1050

27 10 250 4.0 51.9 8 5 1490

28 12 440 4.0 49.7 9.0 1790

29 11 380 5.2 51.5 9.8 1220

The Ha values for all alloys listed in Table IV exceed 8Oe, making them possible to avoid the interference problems mentioned above. Good sensitivity (dfr/dHb) and large signal response (Vm) result in a smaller marker for a resonant marker system.

The values of the magneto-mechanical response of the marker materials listed in Table III under different annealing conditions are summarized in tables V, VI, VII, VIII and IX.

TABLE V

Vm, H of alloy No. 8 in Table III after heat treatment under different conditions in a disc annealing furnace_b1、(fr)_minAnd H_bdfr/dHb value at 6 Oe. The marked direction of the applied magnetic field is the angle between the length direction of the belt and the direction of the magnetic field.

Annealing temperature: 440 ℃ applied field/direction: 1.1KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

9.0 1.4 360 3.9 55.3 8.5 590

10.5 1.4 340 3.8 55.4 8.5 540

10.5 6.0 225 5.0 55.8 9.8 690

Annealing temperature: 400 ℃ applied magnetic field/direction: 1.1KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

9.0 0 300 4.1 53.7 8.3 1170

9.0 7.2 250 5.2 55.9 9.7

Annealing temperature: 340 ℃ applied magnetic field/direction: 1.1KOe/75 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 0 315 7.9 55.7 13.4 420

2.1 0 225 8.0 56.1 12.8 470

TABLE VI

Vm, H of alloy No. 17 in Table III after heat treatment under different conditions in a disc annealing furnace_b1、(fr)_min、H_bdfr/dHb value at 6 Oe. The marked direction of the applied magnetic field is the angle between the length direction of the belt and the direction of the magnetic field.

Annealing temperature: 320 ℃ applied magnetic field/direction: 1.4KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 0 250 6.0 55.3 13.0 670

0.6 1.4 320 6.0 54.0 14.1 620

0.6 3.6 370 7.0 52.2 14.0 630

Annealing temperature: 280 ℃ applied magnetic field/direction: 1.1KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 7.2 390 7.0 53.2 13.9 615

2.1 7.2 240 5.0 53.6 11.5 760

Annealing temperature: 280 ℃ applied magnetic field/direction: 1.1KOe/75 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 7.2 360 6.3 52.9 13.2 630

2.1 7.2 270 5.2 53.2 11.2 860

TABLE VII

Vm, H of alloy No. 24 in Table III after heat treatment under different conditions in a disc annealing furnace_b1、(fr)_min、H_bdfr/dHb value at 6 Oe. The marked direction of the applied magnetic field is the angle between the length direction of the belt and the direction of the magnetic field.

Annealing temperature: 320 ℃ applied magnetic field/direction: 1.1KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 0 280 8.0 54.7 13.1 450

2.1 0 310 7.6 54.7 12.0 500

2.1 7.2 275 8.0 55.1 14.5 450

Annealing temperature: 320 ℃ applied magnetic field/direction: 1.1KOe/75 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/mnute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 0 310 8.2 54.7 13.0 530

0.6 7.2 275 8.2 55.2 15.0 430

2.1 0 290 7.2 54.8 12.0 550

2.1 7.2 270 7.0 55.6 13.5 480

Annealing temperature: 300 ℃ applied magnetic field/direction: 1.1KOe/82.5 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 2.1 300 8.3 54.9 13.7 410

2.1 2.1 300 7.0 54.4 11. 8 480

Annealing temperature: 280 ℃ applied magnetic field/direction: 1.1KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/inute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 0 265 8.4 55.2 12.6 430

2.1 7.2 255 6.8 55.9 12.0 490

TABLE VIII

Vm, H of alloy No.27 in Table III after heat treatment in a disc annealing furnace under different conditions_b1、(fr)_min、H_bdfr/dHb value at 6 Oe. The marked direction of the applied magnetic field is the angle between the length direction of the belt and the direction of the magnetic field.

Annealing temperature: 300 ℃ applied magnetic field/direction: 1.1KOe/82.5 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 2.1 270 6.2 53.8 11.9 690

2.1 2.1 270 5.2 52.9 10.5 870

Annealing temperature: 280 ℃ applied magnetic field/direction: 1.1KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 7.2 290 5.8 53.8 12.0 670

2.1 0 230 6.0 54.3 11.0 720

TABLE IX

Vm, H of alloy No.29 in Table III after heat treatment under different conditions in a disc annealing furnace_b1、(fr)_min、H_bdfr/dHb value at 6 Oe. The marked direction of the applied magnetic field is the angle between the length direction of the belt and the direction of the magnetic field.

Annealing temperature: 320 ℃ applied magnetic field/direction: 1.1KOe/90 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

2.1 7.2 225 4.7 55.2 10.0 570

Annealing temperature: 280 ℃ applied magnetic field/direction: 1.1KOe/75 °

Belt speed stress V_m H_m (f_{r_})_min H_b2 df_r/dH_b

(m/minute) (kg/mm²) (mV) (Oe) (kHz) (Oe) (Hz/Oe)

0.6 0 230 5.8 54.2 11.0 720

0.6 7.2 245 5.2 54.7 11.2 620

The above table indicates that the desired magnetomechanical resonance marker performance can be obtained by the correct combination of alloy chemistry and heat treatment conditions.

Example 2: Fe-Co-Ni-Mo/Cr/Mn-B-Si-C glassy metals

The glassy metal Fe-Co-Ni-Mo/Cr/Mn-B-C-Si series alloy was prepared and characterized as described in example 1. Table X shows the chemical composition, magnetic properties and thermal properties, and Table XI shows the mechanical resonance response values of the alloys in Table X.

Table X

Magnetic and thermal properties of low cobalt content glassy alloys. Tc is the primary crystallization temperature.

Alloy No. component B_s λ_s T_c

Fe Co Ni Mo Cr Mn B Si C (Tesla) (ppm)

(℃)

1 40 14 28 - - - 13 3 2 1.22 19 441

2 40 14 27 1 - - 13 5 - 1.18 18 451

3 40 14 25 3 - - 13 5 - 1.07 13 462

4 40 14 27 - 1 - 13 5 - 1.18 20 462

5 40 14 25 - 3 - 13 5 - 1.07 15 451

6 40 14 25 1 - - 13 5 2 1.15 15 480

7 40 10 31 1 - - 13 5 - 1.12 18 447

8 40 10 31 - 1 - 13 5 - 1.13 18 441

9 40 10 31 - - 1 13 5 - 1.16 18 445

10 40 10 29 - - 3 13 5 - 1.19 17 454

11 40 10 30 - - - 13 5 2 1.13 16 465

TABLE XI

Ha, Vm, H for alloys listed in Table X_b1、(fr)_min、H_b2And H_bThe heat treatment of the alloy was carried out in a continuous disk annealing furnace at 380 ℃ with a ribbon speed of about 0.6m/min and an applied magnetic field of 1.4KOe in the direction across the ribbon width at a value of dfr/dHb of 6 Oe.

Alloy number H₂(Oe) V_m(mV) H_b1(Oe) (f_r)_min(kHz) H_b2(Oe) d_fr/dH_b(Hz/Oe)

1 14 310 8.3 52.5 13.1 870

2 13 350 4.4 51.7 10.0 1640

3 12 250 3.0 51.7 6.4 1790

4 11 320 6.2 51.8 9.8 950

5 10 480 3.7 51.5 8.2 1780

6 9 390 4.1 52.0 8.5 1820

7 10 460 4.2 50.3 8.9 1730

8 10 480 5.2 51.6 9.8 1560

9 12 250 6.5 51.2 10.6 1000

10 10 380 3.5 51.0 7.8 1880

11 9 310 4.0 51.5 8.0 1880

The Ha values for all alloys in Table XI exceed 8Oe, making them possible to avoid the interference problems mentioned above. Good sensitivity (dfr/dHb) and large signal response (Vm) result in smaller markers for resonant marker systems.

Having described all the details of the invention, it is understood that such details need not be strictly adhered to but that further modifications and adaptations may become apparent to one skilled in the art, all within the scope of the invention being determined by the appended claims.

Claims (14)

1. An annealed, magnetic, glassy metal alloy ribbon having at least 70% of its glassy state and consisting, apart from impurities, of a composition of the formula Fe_aCo_bNi_cM_dB_eSi_fC_gComposition wherein M is at least one of molybdenum, chromium and manganese, "a", "b", "c", "d", "e", "f" and "g" are atomic percentages, "a" is from 30 to 45, "b" is from 4 to 40, "c" is from 5 to 45, "d" is from 0 to 3, "e" is from 10 to 25, "f" is from 0 to 15, "g" is from 0 to 2, and a + b + c + d + e + f + g is 100, the strip having been annealed in and along a magnetic fieldThe magnetic field is magnetically saturated to exhibit mechanical resonance at frequencies ranging from 48KHz to 66KHz and has a relatively linear magnetization behavior up to a minimum bias field of 8 Oe.

2. The alloy strip of claim 1 wherein the slope of the mechanical resonance frequency versus bias field curve approaches or exceeds 400Hz/Oe at a bias field of 6 Oe.

3. The alloy strip of claim 1 wherein the bias field at the lowest mechanical resonance frequency is near or above 8 Oe.

4. The alloy strip of claim 1 wherein M is molybdenum.

5. The alloy strip of claim 1 wherein M is chromium.

6. The alloy strip of claim 1 wherein M is manganese.

7. The alloy strip of claim 1 wherein the sum of "b" plus "c" is from 32 to 47 and the sum of "e" plus "f" plus "g" is from 16 to 22.

8. The alloy strip of claim 7 having a composition selected from the group consisting of: fe₄₀Co₃₄Ni₈B₁₃Si₅，Fe₄₀Co₃₀Ni₁₂B₁₃Si₅，Fe₄₀Co₂₆Ni₁₆B₁₃Si₅，Fe₄₀Co₂₂Ni₂₀B₁₃Si₅，Fe₄₀Co₂₀Ni₂₂B₁₃Si₅，Fe₄₀Co₁₈Ni₂₄B₁₃Si₅，Fe₃₅Co₁₈Ni₂₉B₁₃Si₅，Fe₃₂Co₁₈Ni₃₂B₁₃Si₅，Fe₄₀Co₁₆Ni₂₅B₁₃Si₅，Fe₄₀Co₁₄Ni₂₈B₁₃Si₅，Fe₄₀Co₁₄Ni₂₈B₁₆Si₂，Fe₄₀Co₁₄Ni₂₈B₁₁Si₇，Fe₄₀Co₁₄Ni₂₈B₁₃Si₃C₂，Fe₃₈Co₁₄Ni₃₀B₁₃Si₅，Fe₃₆Co₁₄Ni₃₂B₁₃Si₅，Fe₃₄Co₁₄Ni₃₄B₁₃Si₅，Fe₃₀Co₁₄Ni₃₈B₁₃Si₅，Fe₄₂Co₁₄Ni₂₆B₁₃Si₅，Fe₄₄Co₁₄M₂₄B₁₃Si₅，Fe₄₀Co₁₄Ni₂₇Mo₁B₁₃Si₅，Fe₄₀Co₁₄Ni₂₅Mo₃B₁₃Si₅，Fe₄₀Co₁₄Ni₂₇Cr₁B₁₃Si₅，Fe₄₀Co₁₄Ni₂₅Cr₃B₁₃Si₅Fe₄₀Co₁₄Ni₂₅Mo₁B₁₃Si₅C₂，Fe₄₀Co₁₂Ni₃₀B₁₃Si₅，Fe₃₈Co₁₂Ni₃₂B₁₃Si₅，Fe₄₂Co₁₂Ni₃₀B₁₃Si₅，Fe₄₀Co₁₂Ni₂₆B₁₇Si₅，Fe₄₀Co₁₂Ni₂₈B₁₅Si₅，Fe₄₀Co₁₀Ni₃₂B₁₃Si₅，Fe₄₂Co₁₀Ni₃₀B₁₃Si₅，Fe₄₄Co₁₀Ni₂₈B₁₃Si₅，Fe₄₀Co₁₀Ni₃₁Mo₁B₁₃Si₅，Fe₄₀Co₁₀Ni₃₁Cr₁B₁₃Si₅，Fe₄₀Co₁₀Ni₃₁Mn₁B₁₃Si₅，Fe₄₀Co₁₀Ni₂₉Mn₃B₁₃Si₅，Fe₄₀Co₁₀Ni₃₀B₁₃Si₅C₂，Fe₄₀Co₈Ni₃₈B₁₃Si₅，Fe₄₀Co₆Ni₃₆B₁₃Si₅And Fe₄₀Co₄Ni₃₈B₁₃Si₅Where subscripts are atomic percentages.

9. The alloy strip of claim 1 wherein said strip has been heat treated in a magnetic field.

10. The alloy strip of claim 9 wherein said applied magnetic field has a field strength such that said strip is magnetically saturated in the direction of said magnetic field.

11. The alloy strip of claim 10 wherein said strip has a length direction and said applied magnetic field is oriented across the width of the strip at an angle of 75 ° to 90 ° relative to the length direction of the strip.

12. The alloy strip of claim 11 wherein said magnetic field has a strength in the range of 1 to 1.5 KOe.

13. The alloy strip of claim 11 wherein said heat treatment step is for a time in the range of several minutes to several hours at a temperature below the crystallization temperature of the alloy.

14. The alloy strip of claim 1 wherein said heat treatment is carried out in a continuous disc furnace and the strength of said magnetic field is in the range of 1 to 1.5KOeDirected across the width of the belt and angled at 75 ° to 90 ° to the length of the belt, said belt having a width of between 1mm and 15mm and a belt speed of between 0.5m/min and 12m/min and being subjected to a load of between 0 and 7.2Kg/mm²The temperature of the heat treatment is determined such that the temperature of the strip is below the crystallization temperature of the strip and the strip has sufficient fracture plasticity after the heat treatment.