Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C45/00—Amorphous alloys
  • C22C45/04—Amorphous alloys with nickel or cobalt as the major constituent
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
  • H01F1/153—Amorphous metallic alloys, e.g. glassy metals
  • H01F1/15316—Amorphous metallic alloys, e.g. glassy metals based on Co

Definitions

• This invention relates to amorphous metal alloys and, more particularly, to cobalt rich amorphous metal alloys that include certain transition metal and metalloid elements.
• Metallic glasses generally show resistivities greater than 100 micro ohm cm, whereas crystalline and polycrystalline magnetic metals generally show resistivities below 50 micro ohm cm. Also, because of their randomly disordered structures, metallic glasses are typically isotropic in their physical properties, including their magnetization. Because of these two characteristics, metallic glasses have an initial advantage over conventional magnetic metals. However, metallic glasses do not generally show zero magnetostriction. When zero magnetostriction glasses can be found they are generally good soft magnetic metals (R.C. O'Handley, B.A.
• the present invention provides low magnetostriction and zero magnetostriction glassy alloys that are easy to fabricate and thermally stable.
• the alloys have a composition selected from the group consisting of Co73Fe4.5Mn2.5B20' Co 73 Fe 2.5 Mn 4.5 B 20 , Co 73 Fe 2 Mn 5 B 20 20, Co66-Mn 9 Ni 5 B 20 and Co 68.4 Mn 8.3 Ni 3.3 B 20 .
• the amorphous alloys of the invention can be formed by cooling a melt of the composition at a rate of at least about 10 "C/sec.
• a variety of techniques are available, as is now well-known in the art, for fabricating splat-quenched foils and rapid-quenched continuous ribbons, wire, sheet, etc.
• a particular composition is selected, powders of the requisite elements (or of materials that decompose to form the elements, such as nickel-borides, etc.) in the desired proportions are melted and homogenized, and the molten alloy is rapidly quenched either on a chill surface, such as a rotating cooled cylinder, or in a suitable fluid medium, such as a chilled brine solution.
• the amorphous alloys may be formed in air. However, superior mechanical properties are achieved by forming these amorphous alloys in a partial vacuum with absolute pressure less than about 5.5 cm of Hg, and preferably about 100 pm to 1 cm of Hg, as disclosed in U.S. Patent No. 4,154,283 to Ray et al.
• the amorphous metal alloys are at least 50 percent amorphous, and preferably at least 80 percent amorphous, as measured by X-ray diffraction. However, a substantial degree of amorphousness approaching 100 percent amorphous is obtained by forming these amorphous metal alloys in a partial vacuum. Ductility is thereby improved, and such alloys possessing a substantial degree of amorphousness are accordingly preferred.
• Ribbons of these alloys find use in soft magnetic applications and in applications requiring low magnetostriction, high thermal stability (e.g., stable up to about 100°C) and excellent fabricability.
• the magnetostriction measurements were made in fields up to 4 KOe with metal foil strain gauges (as reported in more detail by R .C. O'Handley in Solid State Communications, Vol. 22, p. 485, 1977). The accuracy of these measurements is considered to be within 10 percent of full strain and their strain sensitivity is on the order of 10 -7 .
• Co-rich glass compositions with positive and negative magnetostriction can be added linearly to give zero magnetostriction.
• ⁇ s for Co 70 Fe 10 B 20 and Co 80 B 20 glasses are +4 and -4 x 10 -6 , respectively.
• the rule of linear combination of opposing magnetostrictions (LCOM) has been applied to develop additional zero magnetostriction glasses. Table I lists several such glasses and the drawing shows where they fall in the Co-rich corner of a triangular composition diagram.
• Metalloid type has little effect on the magnitude or sign of magnetostriction in Co-rich glasses (O'Handley in Amorphous Magnetism eds. R. Levy and R. Hasegawa, Plenum Press 1977, p. 379).
• Table II sets forth some typical near-zero magnetostriction compositions.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Dispersion Chemistry (AREA)
• Power Engineering (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Soft Magnetic Materials (AREA)

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Citations (3)

• 1981
  • 1981-11-26 EP EP85101590A patent/EP0161394A1/fr not_active Withdrawn

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