MXPA97007747A - Metal glass alloys for marker supervision systems mechanically resona - Google Patents

Abstract

A vitreous metal alloy consisting essentially of the formula Fea Cob Nic Md Be Sif Cg, wherein M is at least one member selected from the group consisting of molybdenum, chromium and manganese, "ag" is in atomic percentage, " a "varies from about 30 to about 45," b "ranges from about 4 to about 40," c "varies from about 5 to about 45," d "varies from about 0 to about 3," e "varies from about 10. at about 25, "f" ranges from about 0 to about 15 g "g" ranges from about 0 to about 2. The alloy can be molded by rapid solidification into a ribbon, annealed to improve the magnetic properties and formed into a marker which is especially suitable for use in magneto mechanically driven article monitoring systems. Advantageously, the marker is characterized by a relatively linear magnetization response within the frequency regime wherein the harmonic marker systems operate magnetically. The detected voltage amplitudes for the marker are high, and the interference between the monitoring systems based on mechanical resonance and harmonic re-radiance was virtually eliminated.

Description

"METALLIC GLASS ALLOYS FOR MECHANICALLY RESONANT MARKER SUPERVISION SYSTEMS" REFERENCE TO RELATED REQUESTS This is a continuation in part of the Request North American Serial Number 08 / 421,094 filed on April 13, 1995, called Metal Glass Alloys for Mechanically Resonant Marker Supervision Systems.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to metal glass alloys; and more particularly with metallic glass alloys suitable for use in mechanically resonant markers of article monitoring system. 2. Description of the Previous Technique Numerous article monitoring systems are currently available in the market to help identify and / or secure various animate and inanimate objects. The identification of personnel for controlled access to limited areas, and for securing items of merchandise against theft are examples of the purposes for which these systems are employed. An essential component of all monitoring systems is a detector unit or "marker" that is fixed to the object to be detected. Other components of the system include a transmitter and a receiver that are properly placed in an "interrogation" zone. When the object carrying the marker enters the interrogation zone, the functional part of the marker responds to a signal from the transmitter, whose response is detected in the receiver. The information contained in the response signal is then processed for appropriate actions for the application: denial of access, activation of an alarm, and the like. Different types of markers have been released and are in use. In one type, the functional portion of the marker consists of either an antenna and a diode or an antenna and capacitors that form a resonant circuit. When placed in an electromagnetic field transmitted by the interrogation apparatus, the antenna and diode marker generates harmonics of the interrogation frequency at the receiving antenna. The detection of the harmonic or signal level change indicates the presence of the marker. With this type of system, however, the reliability of marker identification is relatively low due to the wide bandwidth of the simple resonant circuit. In addition, the marker must be removed after identification, which is not desirable in such cases as anti-theft systems. A second type of marker consists of a first elongated element of ferromagnetic material of high magnetic permeability placed adjacent to at least a second element of ferromagnetic material, which has higher coercivity than the first element. When subjected to a frequency interrogation of electromagnetic radiation, the marker generates harmonics of the interrogation frequency due to the nonlinear characteristics of the marker. The detection of these harmonics in the receiver coil indicates the presence of the marker. Deactivation of the marker is achieved by changing the state of magnetization of the second element, which can be easily achieved, for example by passing the marker through a direct current magnetic field. Harmonic marker systems are superior to the aforementioned radiofrequency resonant systems due to the improved reliability of marker identification and the simplest deactivation method. However, there are two main problems with this type of system: one is the difficulty of detecting the marker signal at remote distances. The amplitude of the harmonics that are generated by the marker is much smaller than the amplitude of the interrogation signal, limiting the detection isolation widths to less than approximately 0.914 meter. Another problem is the difficulty of distinguishing the marker signal from pseudo-signals generated by other ferromagnetic objects such as belt buckles., pens, staples, etc. Supervision systems that employ detection modes that incorporate the fundamental mechanical resonance frequency of the marker material are especially advantageous systems, as they offer a combination of high detection sensitivity, high operating reliability, and low operating costs. Examples of these systems are disclosed in U.S. Patent Nos. 4,510,489 and 4,510,490 (hereinafter, patents '489 and' 490). The marker in these systems is a strip, or plurality of strips, of known length of a ferromagnetic material, packed with a magnetically harder ferroman (material with higher coercivity) that provides a polarization field to establish the maximum magneto-mechanical coupling. The material of the ferromagnetic marker is preferably a metallic glass alloy ribbon, since the efficiency of the magneto-mechanical coupling in these alloys is very high. The mechanical resonance frequency of the marker material is essentially regulated by the length of the alloy tape and the polarization field strength. When a interrogation signal is found tuned to this resonance frequency, the marker material responds with a large signal field that is detected by the receiver. The large signal field is partially attributed to an improved magnetic permeability of the marker material at the resonance frequency. Various configurations and marker systems for interrogation and detection using the aforementioned principle have been found in the '489 and' 490 patents. In a particularly useful system, the marker material is excited in oscillations by pulses, or bursts, of signal at its resonance frequency generated by the transmitter. When the excitation pulse is terminated, the marker material will experience damped oscillations at its resonance frequency, i.e., the marker material "decreases resonance" after completion of the excitation pulse. The receiver "listens" to the response signal during this period of decreased resonance. Under this arrangement, the monitoring system is relatively immune to interference from the various irradiated or power line sources and thus essentially eliminates the potential for false alarms. A large scale of alloys have been claimed in the '489 and' 490 patents as being appropriate for the marker material, for the various detection systems disclosed. Other metallic glass alloys that carry high permeability are disclosed in US Pat. No. 4,152,144. A predominant problem in the use of electronic article monitoring systems is the tendency for markers in monitoring systems based on mechanical resonance to accidentally activate detection systems that rely on alternative technology, such as marker systems harmonics described above. The non-linear magnetic response of the marker is sufficiently intense to generate harmonics in the alternative system, thus creating an accidental "false" pseudo-response or alarm. The importance of avoiding the interference between, or "contamination" of, different supervisory systems, is readily apparent. Consequently, 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 alternative technologies, such as harmonic re-radiance.

COMPENDIUM OF THE INVENTION The present invention provides magnetic alloys which are at least 70 percent vitreous and, upon annealing to improve the magnetic properties, are characterized by relatively linear magnetic responses in a frequency regime where the harmonic marker systems operate magnetically. These alloys can be molded into a tape using rapid solidification, or otherwise formed into markers having magnetic and mechanical characteristics especially suitable for use in monitoring systems based on the magneto-mechanical drive of the markers. Manifesting in general terms, the vitreous metal alloys of the present invention have a composition consisting essentially of the formula Fea Coj-, Nic M ^ Be Sif Cg, wherein M is selected from molybdenum, chromium and manganese and "a", "b", "c", "d", "e", "f" and "g" are the atomic percentage, "a" varies from about 30 to about 45, "b" varies from about 4 to about 40 and "c" varies from about 5 to about 45, "d" varies from about 0 to about 3, "e" varies from about 10 to about 25, "f" varies from about 0 to about 15, and "g" varies from about 0 to approximately 2. The tapes of these alloys, when they are mechanically resonant at frequencies ranging from approximately 48 to approximately 66 kHz, show a relatively linear magnetization behavior up to an applied field exceeding 8 Oe, as well as the inclination of the frequency resonate te versus the polarization field near or exceeding the level of approximately 400 Hz / Oe exhibited by a conventional mechanical-resonant marker. In addition, the voltage amplitudes detected in the receiver coil of a typical resonant marker system are higher for the fabricated alloy markers of the present invention than those of the existing resonant marker. These particularities ensure that interference between systems based on mechanical resonance and harmonic re-radiance is avoided. The metallic glasses of this invention are especially suitable for use as active elements in markers associated with article monitoring systems employing excitation and detection of the magneto-mechanical resonance described above. Other uses can be found in detectors that use the magneto-mechanical drive and its related effects and in magnetic components that require high magnetic permeability.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood and the additional advantages will become apparent when reference is made to the following detailed description of the preferred embodiments of the invention, and the accompanying drawings, in which: Figure 1 (a) is a representation schematic of the magnetization curve that is taken along the length of an existing resonant marker, where B is the magnetic induction and H is the applied magnetic field; Figure 1 (b) is a schematic representation of the magnetization curve taken along the length of the marker of the present invention, where Ha is a field above which B is saturated; Figure 2 is a schematic representation of a signal profile detected in the receiver coil illustrating the mechanical resonance excitation, the termination of the excitation during time t0 and subsequent to the resonance reduction, where V0 and V] _ are the amplitudes of the signal in the receiver coil at t = t0 and t = t] _ (1 millisecond after t0), respectively; and Figure 3 is a schematic representation of the mechanical resonance frequency fr, and the response signal, V ^, detected in the receiver coil at 1 millisecond after completion of the excitation alternating current field as a function of this field magnetic polarization, H] - ,, where Hj-ji and H] ^ are the polarization fields to which V] _ is at a maximum and fr is at a minimum, respectively.

DESCRIPTION OF THE PREFERRED MODALITIES In accordance with the present invention, magnetic metal glass alloys are provided which are characterized by relatively linear magnetic responses in the frequency region, where the harmonic marker systems operate magnetically. These alloys show all the necessary characteristics to fill the requirements of markers for the supervision systems based on the magneto-mechanical action. Manifesting generally, the alloys of the vitreous metal of the present invention have a composition consisting essentially of the formula Fea Coj ^ Nic M¿ Be Sif Cg, where M is selected from molybdenum, chromium and manganese and "a", " b "," c "," d "," e "," f "and" g "are in atomic percentage," a "varies from approximately 30 to approximately 45," b "varies from approximately 4 to approximately 40 and" c "varies from about 5 to about 45," d "varies from about 0 to about 3," e "varies from about 10 to about 25," f "varies from about 0 to about 15 and" g "varies from about 0 to about 2. The purity of the aforementioned compositions is that which is found in normal commercial practice. The tapes of these alloys are annealed with a magnetic field applied across the width of the tapes at elevated temperatures for a certain period of time. The temperatures of the tape must be less than its crystallization temperature and the thermally treated tape needs to be sufficiently weak to cut. The field strength during annealing is such that the tapes become magnetically saturated along the direction of the field. The annealing time depends on the annealing temperature and typically ranges from a few minutes to a few hours. For commercial production, a continuous reel-to-reel annealing furnace may be preferred. In these cases, the belt runs at speeds that can be graduated to between 0.5 and 12 meters per minute. Annealed tapes having, for example, a length of about 38 millimeters, exhibit relatively linear magnetic response for magnetic fields up to or greater than 8 Oe which is applied in parallel to the direction of the marker length and mechanical resonance within the frequency scale from approximately 48 kHz to approximately 66 kHz. The region of linear magnetic response extends to the level of more than 8 Oe is sufficient to prevent the actuation of most harmonic marker systems. For more stringent cases, the region of linear magnetic response is extended beyond 8 Oe by changing the chemical composition of the alloy of the present invention. Bands annealed to shorter lengths or not longer than 38 millimeters show higher or lower mechanical resonance frequencies than within the range of 48 to 66 kHz. Tapes that have mechanical resonance within the range of about 48 to 66 kHz are preferred. These tapes are short enough to be used as disposable markers. In addition, the resonance signals of these tapes are well separated from the audio and commercial radiofrequency scales.

Most metallic glass alloys that fall outside the scope of this invention typically exhibit either non-linear magnetic response regions and below the 8 Oe level, or Ha levels close to the magnetic operating excitation levels of many systems. of article detection using harmonic markers. The resonant markers composed of these alloys are triggered or accidentally activated and thus contaminate many item detection systems of the harmonic re-radiance variety. There are a few metallic glass alloys outside the scope of this invention that show linear magnetic response for an acceptable field scale. These alloys, however, contain high levels of cobalt, molybdenum or chromium, resulting in increased raw material costs and / or reduced tape molding capacity due to the higher melting temperatures of these constituent elements such as molybdenum or chromium. The alloys of the present invention are advantageous in that they provide, in combination, extended linear magnetic response, improved mechanical resonance operation, good belt molding capability and economy in the production of the usable belt.

In addition to avoiding interference between different systems, the fabricated alloy markers of the present invention generate larger signal amplitudes in the receiver coil than conventional mechanical resonant materials. This makes it possible to reduce either the size of the marker or increase the detection corridor widths, both of which are desirable features of the article monitoring systems. Examples of the metallic glass alloys of the invention include Fe 0 C034 Ni 8 B 13 Si 5, Fe 0 Co 30 Ni 12 B 13 Si 5, Fe 40 Co 26 Ni 16 B 13 Si 5 Fe 4 Co 2 Ni 2 O B 13 Si 5, Fe 40 Co 2 O Ni 22 B 13 Si 5, Fe 40 Co 18 Ni 24 B 13 Si 5, Fe35 Co18 Ni29 B13 Si5, Fe32 Co18 Ni32 B13 Si5, Fe 0 Co16 Ni26 B13 Si5, Fe 0 C ?! Ni28 B13 Si5, Fe40 Co1 Ni28 B16 Si2, Fe 0 Co1 Fe40 Co14 Ni28 B13 Si3 C2, Fe38 Co14 Ni30 B13 Si5, Fe36 C? 1 Ni32 B13 Si5, Fe3 Co14 NIF34 B13 Si5, Fe30 Co14 Ni38 B13 Si5, Fe42 Col4 Ni26 B13 Yes5, Fe44 C014 NÍ2 B13 YES5, Fe4Q ^ 0 ^ 4 NÍ27 Mo ^ B13 YES5, Fe4Q Co14 Ni25 M03 B13 Si5, Fe 0 Co1 Ni27 Rx B13 Si5, Fe 0 Co1 Ni25 Cr3 B13 Si5, Fe 0 C? 1 Ni25 Mox B13 Si5 C2, Fe40 Co12 Ni30 B13 Si5, Fe38 C? 12 Ni32 B13 Si5, Fe42 Co12 Ni30 B13 Si5, Fe 0 C12 Ni26 Bi7 Si5, Fe 0 Co12 Ni28 B15 Si5, Fe40 C010 Ni32 B13 Si5, Fe42 Co10 Ni30 B13 Si5, Fe4 Co10 Ni28 B13 Si5, Fe40 Co10 Ni31 Mo? B13 Si5, Fe 0 Co10 Ni31 Cr! B13 Si5, Fe 0 Co10 Ni31 Mnx B13 Si5, Fe40 Co10 Ni29 Mn3 B13 Si5, Fe40 Cl0 Ni30 B13 Si5 C2, Fe40 Co8 Ni38 B13 Si5, Fe 0 Co6 Ni36 Bi3 Si5, and Fe4Q C04 NÍ38 B 3 YES5, where the subscripts they are in atomic percentage. The magnetization behavior characterized by a B-H curve is shown in Figure 1 (a) for a conventional mechanical resonant marker, where B is the magnetic induction and H is the applied field. The total B-H curve is cut with a non-linear hysteresis circuit existing in the low field region. This non-linear characteristic of the marker results in a greater generation of harmonics, which cause some of the harmonic marker systems to operate, thus the interference between the monitoring systems of different articles. The definition of the linear magnetic response is given in Figure 1 (b). Since a marker is magnetized along the length direction by an external magnetic field, H, the magnetic induction, B, results in the marker. The magnetic response is relatively linear up to Ha, beyond which the marker becomes magnetically saturated. The amount Ha depends on the physical dimension of the marker and its field of magnetic anisotropy. To prevent the resonant marker from being accidentally activated, a monitoring system based on the Ha harmony re-radiance must remain above the intensity region of the operating field of the harmonic marker systems. The marker material is exposed to a constant amplitude excitation signal burst referred to as the excitation pulse, tuned to the frequency of the mechanical resonance of the marker material. The marker material responds to the excitation pulse and generates an output signal in the receiver coil that follows the curve leading to V0 in Figure 2. During the time t0, the excitation is terminated and the marker begins the resonance reduction that is reflects in the output signal that it is reduced from V0 to zero over a period of time. During the time t] _, which is 1 millisecond after the termination of the excitation, the output signal is measured and represented by the quantity V ^. Therefore, V? / VQ is a measure of the resonance reduction. Although the principle of operation of the monitoring system does not depend on the configuration of the waves comprising the excitation pulse, the waveform of this signal is usually sinusoidal. The marker material effects resonance under this excitation. The physical principle that governs this resonance can be summarized as follows: When a ferromagnetic material is subjected to a magnetic field of magnetization, experience a change in length. The fractional change in length, through the original length of the material, is termed as magnetostriction and is represented by the symbol?. Is a positive signature assigned to? if an elongation occurs parallel to the magnetic field of magnetization. When a tape of a material with a positive magnetostriction is subjected to an external field that varies sinusoidally, applied along its length, the tape will undergo periodic changes in length ie the tape will be driven towards oscillations. The external field can be generated, for example, by a solenoid carrying a current that varies sinusoidally. When the half-wave length of the oscillation wave of the tape coincides with the length of the tape, the mechanical resonance results. The resonance frequency fr is provided by the relationship fr = (1 / 2L) (E / D) 0-5, where L is the length of the tape, E is the Young's modulus of the tape, and D is the density of the tape. Magnetostrictive effects are observed in a ferromagnetic material only when the magnetization of the material advances through the magnetization rotation. No magnetostriction is observed when the magnetization process is through the movement of the wall of the magnetic domain. Since the magnetic anisotropy of the marker of the alloy of the present invention is induced by field annealing through the width direction of the marker, a direct current magnetic field, referred to as the polarization field applied to the The length of the direction of the marker length improves the efficiency of the magneto-mechanical response of the marker material. It is also understood in the art that a polarization field serves to change the effective value for E, the Young's modulus, in a ferromagnetic material so that the mechanical resonance frequency of the material can be modified by an appropriate selection of field strength of polarization. The schematic representation of Figure 3 further explains the situation: The resonance frequency, fr, decreases with the polarization field H] - ,, reaching a minimum, (fr) min 'at Hb2 • The response of the signal, V] _, detected, say at = tj in the receiver coil, increases with H ^, reaching a maximum Vm in Hj-j ^. The tilt, say ^ / dH] - ,, near the operating polarization field is an important amount, since it is related to the sensitivity of the supervisory system. Summarizing the foregoing, a tape of a magnetostrictive ferromagnetic material positively when exposed to an alternating current magnetic field in the presence of a direct current bias field, will oscillate at the frequency of the driving alternating current field, and when this frequency matches the mechanical resonance frequency fr of the material, the tape will resonate and provide increased response signal amplitudes. In practice, the polarization field is provided by a ferro-magnet with higher coercivity than the marker material present in the "marker package". Table I lists typical values for Vm, Hj -, ^, (r) min and Hb2 for a conventional mechanical resonant marker based on Fe4Q Í38 M04 B ^ vitreous. The low value of Hfo2 'together with the existence of the non-linear behavior of BH less than H ^ tends to cause a marker based on this alloy to accidentally activate some of the harmonic marker systems, resulting in interference between the systems of supervision of articles based on mechanical resonance and harmonic re-radiance.

TABLE I Typical values for Vm, H ^ i, (fr ^ rnin Hb2 For a conventional mechanical resonant marker are based on Fe Q NÍ38 M04 B? 8 vitreous.This tape at a length of 38. 1 millimeter has mechanical resonance frequencies that vary from approximately 57 and 60 kHz.

Vm (mV) Hbl (Oe) (fr) min (k z> Hb2 (Oe) 150-250 4-6 57.58 5-7 Table II lists the typical values for Ha 'V' Hbl '< fr) min 'Hb2 dfr / dHfc Hb for alloys outside the scope of this patent. The field annealing was carried out in a continuous reel-to-reel furnace at 12.7 millimeters tape width where the tape had a speed of about 0.6 meter per minute at about 1.2 meters per minute.

TABLE II The values for Ha, Vm, Hbl, (fr) min 'Hb2 and dfr / dHb Hfc taken at Hb = 6 Oe for alloys outside the scope of this patent. The field annealing was carried out in a continuous reel-to-reel furnace on a belt at a speed of approximately 0.6 meter per minute at approximately 1.2 meters per minute with a magnetic field of approximately 1.4 kOe applied perpendicular to the length direction of the tape.

Composition (a%) Ha Vm Hbl (fr) min Hb2 dfr / dHb (Pe) (mV) (Pe) (kHz) (Pe) (Hz / Qe) A. C042 Fe40 B13 Si5 22 400 7.0 49.7 15.2 700 B. Co38 Fe40 Ni4 B13 Si5 20 420 9.3 53.8 16.4 500 C. Co2 Fe40 Ni40 B13 Si5 10 00 3 < 0 50 > 2 6-8 2,080 D. Co10 Fe40 Ni27 Mn5 B13 Si5 7 > 5 400 2 > 50 > 5 6-8 2,300 Even though alloys A and B show linear magnetic responses for acceptable magnetic field scales, they contain high levels of cobalt, resulting in increased raw material costs.

The alloys C and D have low H ^ i values and high dfr / dH] - values, the combination of which are not desirable from the point of view of the operation of the resonant marker system.

EXAMPLES Example 1: metallic glasses of Fe-Co-Ni-B-Si 1. Preparation of the Sample The vitreous metal alloys in the Fe-Co-Ni-B-Si series, which they designate as samples number 1 to 29 in Tables III and IV, are rapidly cooled since the fusion after the techniques disclosed by Narasimhan in U.S. Patent No. 4,142,571, the disclosure of which is incorporated herein by reference thereto. All molded parts were manufactured in an inert gas using 100 gram fusions. The resulting tapes, typically 25 micrometers thick and about 12.7 millimeters wide, were determined to be free of significant crystallinity by X-ray diffractometry using Cu-K radiation and differential scanning calorimetry. Each of the alloys was at least 70 percent vitreous and in many cases the alloys were more than 90 percent vitreous. The tapes of these vitreous metal alloys were resistant, bright, hard and ductile. The tapes were cut into small pieces for measurements of magnetization, magnetostriction, Curie temperature and crystallization and density. The tapes for the magneto-mechanical resonance characterization were cut to a length of approximately 38.1 millimeters and then thermally treated with a magnetic field applied across the width of the tapes. The magnetic field strength was 1.1 kOe or 1.4 kOe and its direction was varied between 75 ° and 90 ° with respect to the direction of the tape length. Some of the tapes were thermally treated under tension ranging from zero to about 7.2 kilograms per square millimeter applied along the direction of the tape. The speed of the tape in the reel to reel annealing furnace was changed from approximately 0.5 meter per minute to approximately 12 meters per minute.

Characterization of magnetic and thermal properties Table III lists saturation induction (Bs), saturation magnetostriction (? S), crystallization temperature (Tc) of alloys. The magnetization was measured by a vibration sample magnetometer providing the saturation magnetization value in emu / gram which became the saturation induction using density data. Saturation magnetostriction was measured by the method of a strain gauge that is given in 10-6 or in parts per million. The Curie and crystallization temperatures were measured by an inductance and differential scanning calorimetry method, respectively.

TABLE III The magnetic and thermal properties of vitreous alloys of Fe-Co-Ni-B-Si. The Curie temperatures of alloy number 22 (Tf = 447 ° -C), number 27 (Tf = 430 ° C), number 28 (T = 400 ° C) and 29 (Tf = 417 ° C) could be determined because they are lower than the first crystallization temperatures (Tc).

No Composition (a%) B «- (Tesla)? S (ppm) Tr (° C) Fe Co Ni B Yes 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 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 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 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 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 having a dimension of approximately 38.1 millimeters by 12.7 millimeters by 20 microns was tested by a conventional BH circuit tracer to measure the amount of Ha and then placed on a detector coil with 221 laps It was applied to an alternating current magnetic field along the longitudinal direction of each alloy marker with a direct current bias field change from 0 to about 20 Oe. The sensing coil detected the magneto-mechanical response of the alloy marker to the excitation of alternating current. These marker materials emit mechanical resonance between approximately 48 and 66 kHz. The quantities that characterize the magneto-mechanical response were measured and listed in Table IV for the alloys listed in Table III.

TABLE IV The values of Ha, Vm, Hbl, (fr) min 'Hb2 and dfr / dHb taken at Hb = 6 Oe for the alloys of Table III thermally treated at 380 ° C in a continuous furnace from reel to reel with a belt speed of approximately 1.2 meters per minute and at 415 ° C for 30 minutes (indicated by asterisks). The annealing field was about 1.4 kOe applied perpendicular to the direction of the direction length.

Not of Allocation Ha (0e) Vm (mv) Hh1 (Pe) (f r) min (kHz) H? (0e) df ,, / dHv, (Hz / Qe) 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 20 330 8.0 53.6 14.2 590 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 * 17 390 8.9 49.3 15.9 550 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 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 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 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 All the alloys listed in Table IV exhibit Ha values exceeding 8 Oe, which makes it possible to avoid the interference problem mentioned above. Good sensitivity (dfr / dHj :)) and large response signal (Vm) results in smaller markers for resonant marker systems. The quantities that characterize the magneto-mechanical resonance of the marker material of Table III treated thermally under different annealing conditions are summarized in Tables V, VI, VII, VIII and IX. TABLE V The values of Vm, Hb ?, (fr ^ min 'Hb2' dfr / dHb taken at Hb = 6 Oe for alloy number 8 of Table III, thermally treated under different conditions in an annealing furnace from reel to reel. of the applied field indicated is the angle between the direction of the length of the tape and the direction of the field.

Annealing Temperature: Applied Field / Direction: 1.1 kQe / 90 '440 ° C Stress Speed m un -tirJ-min_ Í! B2 dfr / dHh the Tape (kg / mrn ^) (mV) (0 ~ e) (JHz ~) (CJe) (Hz7? E) ~ (m / minute) 9.0 1.4 360 3.9 55.3 8.5 590 . 5 1.4 340 3.8 55.4 8.5 540 . 5 6.0 225 5.0 55.8 9.8 690 Annealing Temperature: Applied Field / Direction: 1. 1 kQe / 90 ° 400 ° C Stress Speed Ym í-m -Í-Érlmin Ílb2 dfr / dHh the tape (kg / mm ^) (mV) (Oe) (JcHzT- (Oe ") (H" z / 0e) (m / minute) 9.0 0 300 4.1 53.7 8.3 1170 9. 0 7.2 250 5.2 55.9 9.7 Annealing Temperature: Applied Field / Direction: 1.1 k0e / 75c 340 ° C Voltage Speed Yin? Ím- -í-Eri-min Íb2 dfr / dHh the Tape (kg / mm ^) (mV) (Oe) (IcHz) (Oe) (Hz / Oef (m / minute) 0.6 0 315 7.9 55.7 13.4 420 2. 1 0 225 8.0 56.1 12.8 470 TABLE VI The values of Vm, Hb ?, (fr) min 'Hb2' dfr / dHb taken at Hb = 6 Oe for alloy number 17 of Table III, which was thermally treated under different conditions in an annealing furnace reel to reel. The direction of the applied field indicated is the angle between the direction of the length of the tape and the direction of the field. Annealing Temperature: Applied Field / Direction: 1 .4 kOe / 90 ° 320 ° C Voltage Speed Ym? -m --- r-Lmin_ Hb2 dfr / dHh Tape (kg / mm ^) (V) (de) (? zT- (OeT (Hz70e) ~ (m / minute) 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: Applied Field / Direction: 1.1 k? E / 90 ° 280 ° C Voltage Speed Ym üm -L-.ri.min ÍÍb2 dfr / dHb the tape (kg / mm ^) (mV) (Se) ( ] HzT ~ (Oe) (Hz / Oe) (m / minute) 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: Applied Field / Direction: 1, .1 k? e / 75 ° 280 ° C Voltage Speed Ym í-m_ A- Éri-min Ib2 dfr / dHh Tape (kg / mm ^) (mV) (Oe) (IHz) (Oe) (Hz /? E (m / minute) 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 VI I The values of Vm, H ^ i, (fr) min 'Hb2' dfr / dHb taken at = 6 Oe for alloy number 24 of Table III, heat treated under different conditions in an annealing furnace from reel to reel . The direction of the applied field indicated is the angle between the direction of the length of the tape and the direction of the field.

Annealing Temperature: Applied Field / Direction: 1. 1 kQe / 90 ° 320 ° C Voltage Speed Ym -liri-min---b2 dfr / dHh the Tape (kg / mm ^) (mV) (Oe) (JHz ) (CJeJ (Hz7? E) ~ (m / minute) 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: Applied Field / Direction: 1. 1 kOe / 75 320 ° C Voltage Speed Ym í-m J-Eri-min = b2 dfr / dHh the tape (kg / mm ^) (mV) (Ge) ( KHz) (Ce) (H "z / Oe) (m / minute) 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 7.2 170 7.0 55.6 13.5 480 Annealing Temperature: Applied Field / Direction: 1.1 k0e / 82.5 ° 300 ° C Voltage Speed Ym í-m_ -i-iri-min -Íb2 dfr / dHh the Tape (kg / mm ^) (fiv) (Oe) (kHz) (Oe) (Hz / OeF (m / minute) 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: Applied Field / Direction: 1.1 kQe / 90oCc 280 ° C Stress Speed Ym íim_ -iiri-min Í! B2 dfr / dHh the Tape (kg / rnrn ^) (mV) (Oe) (KHz) (Oß) (Hz / Oef (m / minute) 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 The values of Vm, H ^ i, (fr) in 'Hb2' dfr / dHb which are taken at H ^ = 6 Oe for alloy number 27 of Table III, thermally treated under different conditions in a reel annealing furnace to reel. The direction of the applied field indicated is the angle between the direction of the length of the tape and the direction of the field.

Annealing Temperature: Applied Field / Direction: 1. 1 k0e / 82. 5 { 300 ° C Voltage Speed Ym íím -i-.rl.min_. Ííb2 dfr / dHh the Tape (kg / mm2) (mV) (Oe) (JHz) (C3eT (Hz7? E) ~ (m / minute) 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: Applied Field / Direction: 1. 1 kQe / 90 '280 ° C Voltage Speed Ym íím i_.rl.min _ ± > 2 dfr / dHh the tape (kg / mm2) (mV) (Oe) (KHz) (Oe) (H "z / 0e) (m / minute) 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 Values of Vm, Hbl, (fr) my Hb2, dfr / dHb that are taken at HJ-J = 6 Oe for alloy number 29 of the Table I I I, heat treated under different conditions in an annealing furnace from reel to reel. The applied field direction indicated is the angle between the direction of the length of the tape and the direction of the field.

Annealing Temperature: Applied Field / Direction: 1.1 kOe / 90c 320 ° C Voltage Speed Ym üm -__ r_jt? In_ Ííb2 dfr / dHh the Tape (kg / rnrn ^) (mV) < se > (kHz) (Oe) (Hz7? e) ~ (m / minute) 2.1 7.2 225 4.7 55.2 10.0 570 Annealing Temperature: Applied Field / Direction: 1.1 kOe / 75 ° C 280 ° C Speed of Hj-, __rimin b2 dfr / dHh the tape) (Oe) (KHzT- (Oe ") (H ~ z /? E) (m / minute) 0.6 0 230 5.8 54.2 11.0 720 0.6 7.2 245 5.2 54.7 11.2 620 The aforementioned tables indicate that the desired operation of a magneto-mechanical resonant marker can be achieved by appropriate combination of the chemical and thermal treatment conditions of the alloy.

Example 2: Metal Glasses of Fe-Co-Ni-Mo / Cr / Mn-B-Si-C Vitreous metal alloys were prepared in the Fe-Co-Ni-Mo / Cr / Mn-B-Si-C system and characterized as detailed under Example 1. Table X lists the chemical compositions, the magnetic properties and thermal and Table XI lists the quantities that characterize the mechanical resonance responses of the alloys in Table X.

TABLE X Magnetic and thermal properties of vitreous alloys that contain a small amount of cobalt. Tc is the first crystallization temperature.

No Composition (a%) T Alloy Fe Co Ni Mo Cr Mn B Yes c (Tesla) (ppm) (° C) 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 - - - 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 The values of Ha, Vm, H] - ?, (fr) min 'Hb2 and df-VdHb taken at Hj-, = 6 Oe for the alloys listed in Table X thermally treated at 380 ° C in a continuous furnace from reel to reel with a belt speed of approximately 0.6 meter per minute with a 1.4 kOe field applied through the belt.

No Alloy H_ (Oe) Vm (mv) Mbl (?) (Fr) min (kHz) Hb2 < 0e > dfr / dHh (Hz / 0e) 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 All the alloys listed in Table VII exhibit Ha values exceeding 8 Oe, which makes it possible for them to avoid the interference problems mentioned above. A good sensitivity (df-ydH] -,) and a large magneto-mechanical resonance response signal (Vm) result in smaller markers for resonant marker systems. Having thus described the invention in full detail, it will be understood that it does not need to adhere strictly to this detail but rather suggest itself additional changes and modifications for a person skilled in the art, all of them being within the scope of the invention as defined by the appended claims.

Claims (26)

CLAIMS;

1. An alloy of magnetic metallic glass which is at least about 70 percent vitreous, has been annealed to improve the magnetic properties and has a composition consisting essentially of the formula Feb Cob Nic M? Be Sif Cg, wherein M is minus one member that is selected from the group consisting of molybdenum and manganese "a", "b", "c", "d", "e", "f" and "g" are the atomic percentage, "a" varies from about 30 to about 45, "b" ranges from about 4 to about 40 and "c" ranges from about 5 to about 45, "d" ranges from about 0 to about 3, "e" ranges from about 10 to about 25. , "f" ranges from about 0 to about 15 and "g" ranges from about 0 to about 2.

2. An alloy according to claim 1, which has the form of a thermally treated strip that exhibits mechanical resonance within the frequency scale of approximately 48 kHz at approximately 66 kHz, and having a relatively linear magnetization behavior up to a minimum polarization field of approximately 8 Oe.

3. An alloy according to claim 2, wherein the inclination of the mechanical resonance frequency versus the polarization field at about 6 Oe is close to or exceeds about 400 Hz / Oe.

4. An alloy according to claim 2, wherein the polarization field at which the mechanical resonance frequency acquires a minimum that is close to or exceeds about 8 Oe.

5. An alloy according to claim 2, wherein M is molybdenum.

6. An alloy according to claim 2, wherein M is chromium.

An alloy according to claim 2, wherein M is manganese 8.

An alloy according to claim 2, wherein "a" varies from about 30 to about 45, the sum of "b" plus "c" ranges from about 32 to about 47, and the sum of "e" plus "f" plus "g" varies from about 16 to about 22.

The magnetic alloy of claim 8, having a composition that is selected from the group consisting of Fe4Q C034 Nis B13 YES5, Fe4o "C030 N: * - 12 B13 YES5 'Fe40 Co26 Ni16 B13 Si5, Fe 0 Co22 Ni2o B13 Si5, Fe 0 Co20 Ni22 B13 Si5, Fe 0 Co18 Ni24 B13 Si5, Fe35 Co18 Ni2g Si5, Fe32 C? 18 Ni32 B13 Si5, Fe 0 C? 16 Ni26 B13 Si5, Fe 0 Co14 Ni28 B13 Si5, Fe40 C? 1 Ni28 B16 Si2, Fe 0 Co1 Ni28 Bn Si7, Fe40 C? 14 Ni28 B13 Si3 C2, Fe38 Co1 Ni30 B13 Si5, Fe36 C? 14 Ni32 B13 Si5, Fe3 Coi4 Ni3 B13 Si5, Fe30 C14 Ni38 B13 Si5, Fe2 C? 14 Ni26 B13 Si5, Fe C014 Ni24 B13 Si5, Fe40 C? 14 Ni27 Mo? B13 Si5 , Fe 0 Co14 Ni25 Mo3 B13 Si5, Fe4 0 Co1 Ni27 Or? B13 Si5, Fe40 Co14 Ni25 Cr3 B13 Si5, Fe40 Co14 Ni25 M ?? B13 Si5 C2, Fe 0 C? 12 Ni30 B13 Si5, Fe38 Co12 Ni32 B13 Si5, Fe 2 Co12 Ni30 B13 Si5, Fe40 Co12 Ni26 B17 Si5, Fe40 Co12 Ni28 B15 Si5, Fe 0 C10 Ni32 B13 Si5, Fe 2 Co10 Ni30 B13 Si5, Fe44 Co10 Ni28 B13 Si5, Fe 0 Co10 Ni31 M ?! B13 Si5, Fe 0 Co10 Ni31 Crx B13 Si5, Fe 0 Co10 Ni31 Mnx B13 Si5, Fe40 Co? O Ni2g Mn3 B13 Si5, Fe 0 C? 10 Ni30 B13 Si5 C2, Fe 0 C? 8 Ni38 B13 Si5, Fe 0 C ? 6 Ni36 B13 si-5r and Fe40 Co4 N: > -38 B13 YES5, where the subscripts are in atomic percentage.

10. In an article monitoring system adapted to detect a signal produced by the mechanical resonance of a marker within an applied magnetic field, the improvement wherein the marker comprises at least one strip of ferromagnetic material that is at least about 70 percent vitreous, it has been annealed to improve the magnetic properties and has a composition consisting essentially of the formula Fea Co ^ Nic Be Sif Cg, where M is at least one member that is selected from the group consisting of molybdenum , chromium and manganese "a", "b", "c", "d", "e", "f" and "g" are the atomic percentage, "a" varies from approximately 30 to approximately 45, "b" ranges from about 4 to about 40"c" varies from about 5 to about 45, "d" varies from about 0 to about 3, "e" varies from about 10 to about 25, "f" varies from about 0 to about 15, and "g" varies from about 0 to about 2.

11. A system of monitoring of articles according to claim 10, wherein the strip is selected from the group consisting of tape, wire and sheet.

12. An article monitoring system according to claim 11, wherein the strip is a tape.

13. An article monitoring system according to claim 10, wherein the strip exhibits mechanical resonance within the frequency range from about 48 kHz to about 66 kHz, and relatively linear magnetization behavior up to a polarization field of at least 8 Oe.

14. An article monitoring system according to claim 13, wherein the inclination of the mechanical resonance frequency versus the polarization field for the strip at about 6 Oe is close to or exceeds about 400 Hz / Oe.

15. An article monitoring system according to claim 13, wherein the polarization field at which the mechanical resonance frequency of the strip adopts a minimum is close to or exceeds about 8 Oe.

16. An article monitoring system according to claim 13, wherein M is molybdenum.

17. An article monitoring system according to claim 13, wherein M is the chromium element.

18. An article monitoring system according to claim 15, wherein M is the manganese element.

19. An item monitoring system according to claim 13, wherein "a" varies from about 30 to about 45, the sum of "b" plus "c" varies from about 32 to about 47, and the sum of "e" plus "f" plus "g" varies from about 16 to about 22.

20. An article monitoring system according to claim 23, wherein the strip has a composition that is selected from the group consisting of, Fe Q C034 Ñi8 B? 3 YES5, Fe4Q C030 Ni? 2 B? 3 YES5, Fe 0 Co26 Ni16 B13 Si5, Fe 0 Co22 Ni20 B13 Si5, Fe40 C? 20 Ni22 B13 si5 'Fe40 Co18 Ni24 B13 si5 > Fe35 Co18 Ni29 if5 'Fe32 C? 18 Ni32 B13 Si5, Fe 0 C? 16 Ni26 B13 Si5, Fe40 C014 Ni28 Bi3 Si5, Fe40 C? 1 Ni28 B16 Si2, Fe40 Co14 Ni28 Bu Si7, Fe40 Co14 Ni28 B13 Si3 C2, Fe38 Co14 Ni30 B13 Si5, Fe36 C14 Ni32 Bi3 Si5, Fe34 C014 N3434 B13 Si5, Fe30 Co1 Ni38 Bi3 Si3, Fe2 C1 Ni26 B13 Si5, Fe4 C? 14 Ni24 B13 Si5, Fe40 Co14 Ni27 Mox B13 Si5, Fe0 Co14 Ni25 M03 B13 Si5, Fe40 Co1 N2727 Crx B13 Si5, Fe40 Co14 Ni25. Cr3 B13 Si5, Fe40 Co14 Ni25 M ?? B13 Si5 C2, Fe 0 Co12 Ni30 B13 Si5, Fe38 Co12 Ni32 B13 Si5, Fe42 Co12 Ni30 B13 Si5, Fe 0 Co? 2 Ni26 B17 Si5, Fe40 Co12 Ni28 B15 Si5, Fe 0 C? Or Ni32 B13 si5 'Fe42 o10 Ni30 Bi3 Si5, Fe 4 Co10 Ni28 B13 Si5, Fe 0 Co10 Ni31 Mo? B13 Si5, Fe40 Co10 Ni13 B13 Si5, Fe40 Co10 Ni2g Mn3 B13 Si5, Fe 0 Co10 Ni30 B13 Si5 C2, Fe 0 Co8 N38 C13 Si5, Fe40 Co6 Ni36 B13 S? 5 and Fe40 Co4 N: > -38 B? 3 YES5, where the subscripts are in atomic percentage.

21. An alloy according to claim 2, which has been thermally treated with a magnetic field.

22. An alloy according to claim 21, wherein the magnetic field is applied to a strength or field strength such that the strip becomes magnetically saturated along the direction of the field.

An alloy according to claim 22, wherein the strip has a length direction and the magnetic field is applied across the width direction of the strip, the direction of the magnetic field ranges from about 75 ° C to about 90 ° C with respect to the length direction of the strip.

24. An alloy according to claim 23, wherein the magnetic field has a magnitude ranging from about 1 to 1.5 kOe.

An alloy according to claim 23, wherein the heat treatment step is carried out for a period of time ranging from a few minutes to a few hours at a temperature lower than the crystallization temperature of the alloy.

26. An alloy according to claim 2, wherein the heat treatment is carried out in a continuous reel-to-reel furnace, the magnetic field has an amplitude ranging from about 1 to 1.5 kOe which is applied through the width direction of the strip providing an angle ranging from about 75 ° to about 90 ° with respect to the length direction of the strip and the strip having a width ranging from about one millimeter to about 15 millimeters and a varying speed from about 0.5 meter per minute to about 12 meters per minute, and is under a voltage ranging from about zero to about 7.2 kilograms per square millimeter, at the temperature of the heat treatment is determined in such a way that the temperature of the strip is less than its temperature of crystallization and the strip, when being thermally treated, is sufficiently ductile to be cut.