Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C45/00—Amorphous alloys
  • C22C45/02—Amorphous alloys with iron as the major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
  • C22C27/02—Alloys based on vanadium, niobium, or tantalum

Definitions

• the invention relates to metallic glasses having high permeability, low magnetostriction, low coercivity, low ac core loss, low exciting power and high thermal stability.
• metallic glasses are metastable materials lacking any long range order.
• X-ray diffraction scans of glassy metal alloys show only a diffuse halo similar to that observed for inorganic oxide glasses.
• Metallic glasses have been disclosed in US-A-3 856 513. These alloys include compositions having the formula M a Y b Z e , where M is a metal selected from the group consisting of iron, nickel, cobalt, vanadium and chromium, Y is an element selected from the group consisting of phosphorus, boron and carbon and Z is an element selected from the group consisting of aluminum, silicon, tin, germanium, indium, antimony and beryllium, "a” ranges from about 60 to 90 atom percent, "b” ranges from about 10 to 30 atom percent and "c” ranges from about 0.1 to 15 atom percent.
• M is a metal selected from the group consisting of iron, nickel, cobalt, vanadium and chromium
• Y is an element selected from the group consisting of phosphorus, boron and carbon
• Z is an element selected from the group consisting of aluminum, silicon, tin, germanium, indium, antimony and beryllium
• metallic glassy wires having the formula T i X j , where T is at least one transition metal and X is an element selected from the group consisting of phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium, beryllium and antimony, "i” ranges from about 70 to 87 atom percent and "j” ranges from about 13 to 30 atom percent.
• T is at least one transition metal
• X is an element selected from the group consisting of phosphorus, boron, carbon, aluminum, silicon, tin, germanium, indium, beryllium and antimony
• i ranges from about 70 to 87 atom percent
• j ranges from about 13 to 30 atom percent.
• Metallic glasses are also disclosed in US-A-4 067 732 issued January 10, 1978. These glassy alloys include compositions having the formula M a M' t ,Cr, : M" d B e , where M is one iron group element (iron, cobalt and nickel), M' is at least one of the two remaining iron group elements, M" is at least one element of vanadium, manganese, molybdenum, tungsten, niobium and tantalum, Bis boron, "a” ranges from about 40 to 85 atom percent, "b” ranges from 0 to about 45 atom percent, "c” and “d” both range from 0 to about 20 atom percent and “e” ranges from about 15 to 25 atom percent, with the provision that "b", "c” and “d” cannot be zero simultaneously.
• Such glassy alloys are disclosed as having an unexpected combination of improved ultimate tensile strength, improved hardness and improved thermal stability.
• FR-A-2 376 218 glassy alloys comprising about 63 to 83 atom percent iron and/or cobalt, 0 to about 60 atom percent of which may be replaced by nickel, about 2 to 12 atom percent at least one element selected from the group consisting of molybdenum, tungsten, niobium and titanium and about 15 to 25 atom percent at least one element selected from the group consisting of boron, phosphorus and carbon, but containing no silicon are known.
• the US ⁇ A ⁇ 4 140 525 discloses glassy alloys consisting of 56 to 68 atom percent iron, 4 to 9 atom percent chromium, 1 to 6 atom percent molybdenum and 27 to 29 atom percent boron.
• the EP-A-20 937 discloses. at least 90% amorphous metal alloys consisting essentially 80 to 82 atom percent iron, 12.5 to 14.5 atom percent boron, 2.5 to 5.0 atom percent silicon and 1.5 to 2.5 atom percent carbon.
• the EP-A-49 770 discloses special amorphous alloys having the formulae Fe 81 B 13.5 Si 3.5 C 2 , Fe s ,B '4 Si s and Fe 79 B 16 Si 5 .
• metallic glasses possessing a combination of higher permeability, lower magnetostriction, lower coercivity, lower core loss, lower exciting power and higher thermal stability than prior art metallic glasses are required for specific applications such as tape recorder head, relay cores, transformers and the like.
• metallic glasses having a combination of high permeability, low saturation magnetostriction, low coercivity, low ac core loss, low exciting power and high thermal stability.
• the metallic glasses consist of 62 to 79 atom percent of iron, 2 to 8 atom percent of at least one element selected from the group consisting of nickel, cobalt, and mixtures thereof, 2 to 4 atom percent of at least one element selected from the group consisting of chromium, molybdenum, tungsten, vanadium, niobium, tantalum, zirconium and hafnium, 17 to 28 atom percent of boron, from 0.5 to 6 atom percent of said boron being replaced with silicon and up to 2 atom percent of boron being, optionally, replaced with carbon, plus incidental impurities.
• the metallic glasses of the invention are suitable for use in tape recorder heads, relay cores, transformers and the like.
• a concentration of less than about 1 atom percent of Cr, Mo, W, V, Nb, Ta, Ti, Zr and/or Hf does not result in sufficient improvement of the properties of permeability, saturation magnetostriction, coercivity, ac core loss and thermal stability.
• a concentration greater than about 6 atom percent of at least one of these elements results in an unacceptably low Curie temperature.
• the metal content is preferably substantially iron, with up to about 8 atom percent nickel and/or cobalt in order to compensate the reduction of the room temperature saturation magnetization due to the presence of chromium, molybdenum, tungsten, niobium, tantalum, titanium, zirconium and/or hafnium.
• nickel increases permeability.
• the replacement of boron with silicon and carbon provides said glass with a metalloid element selected from the group consisting of substantially boron and from 0.5 to 4 atom percent silicon, and boron plus silicon together with from 0 to 2 atom percent carbon.
• the metallic glasses according to the invention consist of 70 to 79 atom percent iron, 2 to 4 atom percent of at least one element selected from the group consisting of nickel, cobalt and mixtures thereof, 2 to 4 atom percent of an element selected from the group consisting of molybdenum and chromium and 17 to 22 percent of an element selected from the group consisting of boron, silicon and mixtures thereof.
• the alloys according to the invention are at least 85 percent amorphous and comprise discrete particles of its constituents, said particles having an average size ranging from 0.1 ⁇ m to 0.3 ⁇ m and an average said discrete particles occupy an average volume fraction of 0.005 to 0.01.
• Examples of metallic glasses of the invention include (the subscripts are in atom percent). The purity of all alloys is that found in normal commercial practice.
• chromium, molybdenum, tungsten, vanadium, niobium, tantalum, titanium, zirconium and/or hafnium raises the crystallization temperature while simultaneously lowering the Curie temperature of the glassy alloy.
• the increased separation of these temperatures provided ease of magnetic annealing, that is, thermal annealing at a temperature near the Curie temperature.
• thermal annealing at a temperature near the Curie temperature.
• annealing a magnetic material close to its Curie temperature generally results in improved properties.
• annealing can be easily accomplished at elevated temperatures near the Curie temperature and below the crystallization temperature. Such annealing cannot be carried out for many alloys similar to those of the invention but lacking these elements.
• too high a concentration of chromium, molybdenum, tungsten, vanadium, niobium, tantalum, titanium, zirconium and/or hafnium reduces the Curie temperature to a level that may be undesirable in certain applications.
• the metalloid content ranges from 17 to 26 atom percent for maximum thermal stability.
• Preferred metallic glass systems are as follows:
• Magnetic permeability is the ratio of induction to applied magnetic field. A higher permeability renders a material more useful in certain applications such as tape recorder heads, due to the increased response.
• the frequency dependence of permeability of the glassy alloys of the invention is similar to that of the 4-79 Permalloys in the medium-to-high frequency range (1-50 kHz), and at higher frequencies (about 50 kHz to 1 MHz), the permeability is comparable to that of the supermalloys.
• Saturation magnetostriction is the change in length under the influence of a saturating magnetic field.
• a lower saturation magnetostriction renders a material more useful in certain application such as tape recorder heads.
• Magnetostriction is usually discussed in terms of the ratio of the change in length to the original length, and is given in ppm.
• Prior art iron rich metallic glasses evidence saturation magnetostrictions of about 30 ppm as do metallic glasses without the presence of the any of the elements belonging to the IVB, VB and VIB columns of the periodic table such as molybdenum.
• a prior art iron rich metallic glass designated for use in high frequency applications and having the composition Fe 79 B 16 Si 5 has a saturation magnetostriction of about 30 ppm.
• a metallic glass of the invention having the composition Fe 75 Ni 4 Mo 3 B 16 Si 2 has a saturation magnetostriction of about 20 ppm.
• a lower saturation magnetostriction leads to a lower phase angle between the exciting field and the resulting induction. This results in lower exciting power as discussed below.
• Ac core loss is that energy loss dissipated as heat. It is the hysteresis in an ac field and is measured by the area of a B-H loop for low frequencies (less than about 1 kHz) and from the complex input power in the exciting coil for high frequencies (about 1 kHz to 1 MHz). The major portion of the ac core loss at high frequencies arises from the eddy current generated during flux change. However, a smaller hysteresis loss and hence a smaller coercivity is desirable. A lower core loss renders a material more useful in certain applications such as tape recorder heads and transformers. Core loss is discussed in units of watts/kg.
• Prior art heat-treated metallic glasses typically evidence ac core losses of about 0.05 to 0.1 watts/kg at an induction of 0.1 Tesla and at the frequency range of 1 kHz.
• a prior art heat-treated metallic glass having the composition Fe 4o Ni 36 Mo 4 B 2o has an ac core loss of 0.07 watts/kg at an induction of 0.1 Tesla and at the frequency of 1 kHz
• a metallic glass having the composition Fe, 6 Mo 4 B 2o has an ac core loss of 0.08 watts/kg at an induction of 0.1 Tesla and at the same frequency.
• a metallic glass alloy of the invention having the composition Fe 75 Ni 4 Mo 3 B 16 Si 2 has an ac core loss of 0.02 watts/kg at an induction of 0.1 Tesla and at the same frequency.
• Exciting power is a measure of power required to maintain a certain flux density in a magnetic material. It is therefore desirable that a magnetic material to be used in magnetic devices has an exciting power as low as possible.
• the phase shift is also related to the magnetostriction in such a way that a lower magnetostriction value leads to lower phase shift. It is than advantageous to have the magnetostriction value as low as possible.
• prior art iron-rich metallic glasses such as Fe 79 B 16 Si 5 have the magnetostriction value near 30 ppm, in contrast to the magnetostriction value of about 20 ppm of the metallic glasses of the present invention.
• This difference results in a considerable phase shift difference.
• optimally annealed prior art metallic glass Fe 79 B 16 Si 5 has 6 near 70° while the metallic glasses of the present invention have 5 near 50°. This results, for a given core loss, in a higher exciting power by a factor of two for the prior art metallic glass than the metallic glass of the present invention.
• Crystallization temperature is the temperature at which a metallic glass begins to crystallize.
• a higher crystallization temperature renders 'a material more useful in high temperature applications and, in conjunction with a Curie temperature that is substantially lower than the cyrstallization temperature, permits magnetic annealing just above the Curie temperature.
• Some metallic glasses crystallize in multiple steps.
• the first crystallization temperature (the lowest value of the crystallization temperatures) is the meaningful one as far as the materials' thermal stability is concerned.
• the crystallization temperature as discussed herein is measured by differential scanning calorimetry. Prior art glassy alloys evidence crystallization temperatures of about 660 K to 750 K.
• a metallic glass having the composition Fe 78 MO 2 B 20 has a crystallization temperature of 680 K
• a metallic glass having the composition Fe 74 MO 6 B 20 has a crystallization temperature of 750 K
• metallic glasses of the invention evidence increases in crystallization temperatures to a level above 750 K.
• the magnetic properties of the metallic glasses of the present invention are improved by thermal treatment, characterized by choice of annealing temperatures (T a ), holding time (t a ), applied magnetic field (either parallel or perpendicular to the ribbon direction and in the ribbon plane), and post-treatment cooling rate.
• T a annealing temperatures
• t a holding time
• applied magnetic field applied magnetic field
• post-treatment cooling rate post-treatment cooling rate.
• the optimal properties are obtained after an anneal which causes the controlled precipitation of a certain number of crystalline particles from the glassy matrix. Under these conditions, for compositions having boron content ranging from about 17 to 20 atom percent, the discrete particles have a body-centered cubic structure.
• the particles are composed essentially of iron, up to 22 atom percent of the iron being adapted to be replaced by at least one of nickel, cobalt, chromium, molybdenum, tungsten, vanadium, niobium, tantalum, titanium, zirconium, hafnium, silicon and carbon.
• the discrete particles consist essentially of a mixture of particles, a major portion of which mixture contains particles having a crystalline Fe 3 B structure.
• the particles of such portion are composed of iron and boron, up to 14 atom percent of the iron being adapted to be replaced by at least one of nickel, cobalt, chromium, molybdenum, tungsten, vanadium, niobium, tantalum, titanium, zirconium and hafnium and up to 2 atom percent of the boron being adapted to be replaced by carbon.
• a small number of such particles introduces a certain decrease in the average domain wall spacing with concomitant decrease in core loss. Too large a number of particles increases the coercivity and thus the hysteresis loss.
• a metallic glass of the present invention with composition Fe 75 Ni 4 MO 3 B 16 Si 2 has a combination of low loss and high permeability with a coercivity of only 2 A/m when optimally annealed.
• an optimally annealed prior art metallic glass Fe 79 B 16 Si 5 has a coercivity of about 8 A/m.
• the crystalline particle size in the optimally heat-treated materials of the present invention ranges between 100 and 300 nm, and their volume fraction is less than 1%.
• the interparticle spacing is of the order of 1-10 pm.
• the metallic glasses of the invention have a combination of high permeability, low saturation magnetostriction, low coercivity, low ac core loss, low exciting power and high crystallization temperature and are useful as tape heads, relay cores, transformers and the like.
• the metallic glasses of the invention are prepared by cooling a melt of the desired composition at a rate of at least about 10 5 °C/sec, employing quenching techniques well known to the metallic glass art; see e.g., US-A-3,856,513.
• the metallic glasses are substantially completely glassy, that is, at least 90% glassy, and consequently possess lower coercivities and are more ductile than less glassy alloys.
• a variety of techniques are available for fabricating continuous ribbon, wire, sheet, etc. Typically, a particular composition is selected, powders or granules of the requisite elements in the desired portions are melted and homogenized and the molten alloy is rapidly quenched on a chill surface such as a rapidly rotating cylinder.
• Ribbons having compositions given by Fe, oo -a- b - e - d Ni a Mo b B e Si d and having dimensions about 1 to 2.5 cm wide and about 25 to 50 ⁇ m thick were formed by squirting a melt of the particular composition by overpressure of argon onto a rapidly rotating copper chill wheel (surface speed about 1500 to 3000 cm/sec).
• Molybdenum content was varied from 1 to 6 atom percent, for which substantially glassy ribbons were obtained. Molybdenum content higher than 6 atom percent reduced the Curie temperature to an unacceptable low value.
• Permability, magnetostriction, core loss, magnetization and coercive force were measured by conventional techniques employing B-H toops, metallic strain gauges and a vibrating sample magnetometer. Curie temperature and crystallization temperature were measured respectively by an induction method and differential scanning calorimetry. The measured values of room temperature saturation induction, Curie temperature, room temperature saturation magnetostriction and the first crystallization temperature are summarized in Table I below. The magnetic properties of these glassy alloys are annealing are presented in Table II. Optimum annealing conditions for the metallic glass Fe 75 Ni 4 MO 3 B 16 Si 2 and the obtained results are summarized in Table III. Frequency dependence of permeability and ac core loss of this optimally annealed alloy are listed in Table IV.
• the optimally heat-treated metallic glass Fe 75 Ni 4 MO 3 B 16 Si 2 of the present invention has a coercivity reaching as low as 2.5 A/m and yet has a low core loss of 6.5 W/kg and permeability of 12500 at 50 kHz and at the induction level of 0.1 Tesla.
• the combination of these properties make these compositions suitable for high frequency transformer and tape-head applications.
• Ribbons having compositions given by Fe 100-a-b-c-d M a -M' b -B c -Si d when M is nickel and/or cobalt, M' is one of the elements chromium, molybdenum, tungsten, vanadium, niobium, tantalum, titanium, zirconium and hafnium, and having dimensions about 1 cm wide and about 25 to 50 ⁇ m thick were formed as in Example 1.
• Metal "M”' content was varied from 1 to 6 atom percent, for which substantially glassy ribbons were obtained. Higher metal “M”' content reduced the Curie temperature to an unacceptably low value.
• a combination of low ac core loss and high permeability at high frequency is achieved in the metallic glasses of the present invention.
• the thermal stability is also shown to be excellent as evidenced by high crystallization temperature.
• the metal "M”' content was varied from 1 to 6 atom percent, and the carbon content “e” was up to 2 atom percent for which substantially glassy ribbons were obtained.
• the metal "M"' content greater than about 6 atom percent reduced the Curie temperature to an unacceptably low value.
• the magnetic and thermal data are summarized in Table VII below.
• the magnetic properties of these metallic glasses after annealing are presented in Table VIII.
• a combination of low ac core loss, high permeability, and high thermal stability of the metallic glasses of the present invention renders these compositions suitable in the magnetic cores of transformers, recording heads and the like.

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• 1982
  • 1982-05-24 DE DE8282104504T patent/DE3274562D1/de not_active Expired
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