Bell Telephone Laboratories

At&t Bell Laboratories

At&t Technologies, Inc.

Gilbert Y Chin

Richard C Sherwood

Sungho Jin

Jack H Wernick

John T Plewes

Bud Caesar Wonsiewicz

Henryk Temkin

Aland K Chin

Martin L Green

Chester M Bordelon

Chester M Boredelon

Disclosed are magnetically soft ferritic multiphase Fe-Cr-Ni alloys containing at least about 82 weight percent Fe, between about 3 and about 10 weight percent Cr, and between about 2 and about 8 weight percent Ni, a method for producing such alloys, and devices comprising such an alloy body. The method comprises a low-temperature anneal in the (.alpha.+.gamma.) region of the Fe-Cr-Ni phase diagram. Inventive alloys typically have a coercive force H.sub.c no more than about 3.0 Oe, preferably no more than about 2.0 Oe, a maximum permeability .mu..sub.m of at least about 1500 G/Oe, preferably at least about 2500 G/Oe, and contain at least about 5 volume percent non-.alpha.-phase material, typically .alpha.'- and .gamma.-phase material. Inventive alloys typically also have yield strength to 0.2% offset of at least about 26.10.sup.7 Pa (40.10.sup.3 psi), elongation to fracture of at least about 15%, good formability and rust resistance. Alloys according to the invention can advantageously be used in devices comprising a magnetically soft body, for instance, in electro-acoustic transducers, e.g., in telephone receivers, recording heads, pole pieces, and armatures.

Magnetically soft ferritic Fe-Cr-Ni alloys

Disclosed are magnetically soft ferritic multiphase Fe-Ni alloys having a Ni content in the range of about 4 to about 16 weight percent, devices containing a body fabricated from such alloys, and method for heat treating such body. Appropriate heat treatment comprises a low-temperature anneal in the two-phase (.alpha.+.gamma.) region of the Fe-Ni phase diagram, and typically results in improved magnetic properties. In particular, alloys according to the invention having x weight percent of Ni have a maximum permeability .mu..sub.m at least as large as 1.5[25(16-x).sup.2 ]G/Oe. The alloys typically also have a coercive field H.sub.c at most as large as 0.7[0.65(1+0.6x)]Oe, a saturation induction B.sub.s of at least about 20 kG, a maximum incremental permeability .DELTA..mu., measured with an applied a.c. field of about 0.005 Oe, of at least about 150 G/Oe, and a yield strength to 0.2 percent offset of at least about 40 10.sup.3 psi, with all the material properties measured at room temperature. Alloys according to the invention can advantageously be used in devices comprising a magnetically soft body, for instance in electro-acoustic transducers, e.g., in telephone receivers.

Ferritic Fe-Ni magnetic alloys

In view of rising cobalt costs, low-cobalt alloys such as, e.g., Fe-Cr-Co alloys are finding increasing use in the manufacture of permanent magnets. Desired magnetic energy product of such magnets is typically at least 1 million gauss-oersted. In the interest of maximizing magnetic energy product per unit weight cobalt, low-cobalt Fe-Cr-Co alloys are processed by solidifying a bulk object from a melt, annealing, quenching, and aging by cooling at rates in a range of 0.1 to 2 degrees C. per hour in a magnetic field. Cold working prior to aging may be used to further enhance magnetic energy product. Resulting magnets have optimized maximum magnetic energy product (BH).sub.max per unit weight cobalt comprised in an alloy.

Low-cobalt Fe-Cr-Co permanent magnet alloy processing

Localized nonuniformities in semiconductor crystals are analyzed by scanning the semiconductor surface with an electron beam and detecting and analyzing the radiation that is generated at the semiconductor surface by the electron beam and which passes through the semiconductor crystal.

Method of analyzing localized nonuniformities in luminescing materials

A method is disclosed for making a metallic body having desirable magnetic properties. The metallic body is made from an alloy which contains Fe, Cr, and Co and which may also contain one or several additional ferrite forming elements such as, e.g., Zr, Mo, V, Nb, Ta, Ti, Al, Si, or W. According to the disclosed method the alloy is cooled at a rate of at least 60 degrees C. per hour from an initial temperature at which the alloy is in an essentially single phase alpha state to a second temperature which is in a vicinity of 600 degrees C. Subsequently, the alloy is cooled at a second, slower rate to a third temperature which is in the vicinity of 525 degrees C. The disclosed method allows for a relatively broad range of initial temperatures, is relatively insensitive to compositional variations of the alloy, and permits simple reclamation of suboptimally treated parts. As a consequence, the method is particularly suited for large scale industrial production of permanent magnets as may be used, e.g., in relays, ringers, and electro-acoustic transducers.

Fe-Cr-Co magnetic alloy processing

Alloy compositions based on ternary alloys of the chromium-cobalt-iron system modified by addition of zirconium molybdenum, niobium, vanadium, titanium, and/or aluminum, are found to manifest improved formability. Exemplary compositions are magnetic and evidence coercivities of 350-550 Oe., remanent magnetizations of from 10,000 - 7,500 Gauss, and maximum energy products in excess of one million. Improvement in formability may take the form of room temperature stamping, sometimes in air, to final configurations including curvatures of radius equal to thickness. Novel compositions particularly desirable from such standpoint necessarily contain zirconium together with aluminum, niobium, and/or titanium.

Growing community of inventors

Berkeley Heights, NJ, United States of America

Gilbert Y Chin