US3637442A - Process for producing plastically deformed iron-rhodium base alloy bodies - Google Patents

Process for producing plastically deformed iron-rhodium base alloy bodies Download PDF

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Publication number
US3637442A
US3637442A US615433A US3637442DA US3637442A US 3637442 A US3637442 A US 3637442A US 615433 A US615433 A US 615433A US 3637442D A US3637442D A US 3637442DA US 3637442 A US3637442 A US 3637442A
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cold
iron
plastically deformed
transition
magnetic
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James S Kouvel
James M Lommel
Thomas E Douglas
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General Electric Co
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General Electric Co
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties

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  • FIG. 0! Search 1 face-centered cubic and then heat treating the final at a temperature no lower than about 235 C. to produce a CsCl- References Cited type ordered crystal structure having an abrupt magnetic transition.
  • the alloys with which this invention deals are iron-rhodium base alloys having in the heat-treated condition a CsCl-type ordered crystal structure, which alloys may or may not contain additional alloying elements. These alloys undergo an antiferromagnetic-ferromagnetic transition which occurs abruptly at different temperatures depending upon the precise composition of the alloy.
  • iron-rhodium binary alloys for example as disclosed in General Electric Research Report No. 61 RL 2870M, Nov. 1961, Kouvel et al.
  • iron-rhodium alloys such as those disclosed in US. Pat. No. 3,144,324, Bither, .lr., Aug. 11, 1964 and US. Pat. No. 3,144,325, Walter, Aug. 11, 1964, constitute examples of iron-rhodium materials amenable to the process of the present invention.
  • FIG. 1 is a graph of magnetization (per gram) as a function of temperature showing the manner in which a severely coldworked sample (i.e., filings) recovers its rapid magnetic transition after it is heated to about 510 k.(235 C.).
  • FIG. 2 is a graph similar to FIG. 1 showing the manner in which the nature of the magnetic transition can be varied by the present process.
  • the present invention is concerned with a process for producing plastically deformed shapes of iron-rhodium base alloys by first hot reducing a starting body to some preselected intermediate thickness and then cold working the body from the intermediate thickness down to a final desired thickness or shape.
  • cold reduction it is necessary to effect intermediate anneals between cold reduction stages to maintain the integrity of the material.
  • the material Upon being finally cold reduced, the material does not exhibit an abrupt magnetic transition.
  • an abrupt transition can be obtained in the worked material by subjecting it to a final heat treatment no lower than about 235 C. and preferably not less than about 425 C.
  • the abruptness of the transition can be changed varying amounts, depending upon the degree of work, until an essentially linear magnetic transition is obtained.
  • iron-rhodium and iron-rhodium containing minor amounts of various alloying agents are very hard materials and therefore have not, prior to this invention, been produced in small sizes by mechanical shaping procedures. That is, they have not been produced in a plastically deformed condition.
  • iron-rhodium base alloys upon being subjected to some cold reduction, transform from an ordered body-centered cubic crystallographic arrangement to a disordered face-centered cubic crystallographic arrangement. In the face-centered cubic condition, the material is presumably more susceptible to cold work.
  • a starting body of an ironrhodium material for example a cast ingot, is initially heated to an elevated temperature not lower than about 850 C. and hot reduced to some lesser thickness.
  • the hit reduction can be effected by various means such as hot rolling, hot forging or hot extrusion.
  • the material is then cold reduced to some preselected final thickness.
  • the material undergoes at least a partial phase transformation from the ordered bodycentered cubic to the disordered face-centered cubic crystallographic arrangement. In this cold-worked condition, the material will not possess the abrupt antiferromagnetic-ferromagnetic transition that is characteristic of annealed ironrhodium base alloys.
  • the abrupt magnetic transition can be obtained in the plastically deformed material if it is heated to a temperature no lower than about 235 C. (510 K.).
  • a substantially higher temperature should be used both to speedup the transformation from the face centered cubic to the body-centered cubic structure and to improve the abruptness of the magnetic transition.
  • an ingot of FeRh 0.3 inch x 0.3 inch x 3 inches in size was cast and then annealed in vacuum at 975 C. for 26 hours to homogenize the composition. Homogenization can be effected at temperatures ranging from about 850 to 1',000 C., for example.
  • the ingot was then cut into three pieces, each of the pieces being 0.3 inch X 0.3 inch X 1 inch in dimension. Two of the samples were hot forged and rolled at temperatures between 850 to 1,00 0 C. to 50 mils and one piece was hot forged and rolled directly to 25 mils.
  • the specimens were put between stainless steel sheets and cold-pack rolled in reduction stages of about 5 percent per pass to a final thickness of about 10 mils. Pack-rolling is not required but due to the comparatively small size of the samples it was expeditious in this instance. Between cold rolling stages, the samples were annealed at about 950 C. for stress relieving purposes.
  • the manner in which the magnetic properties of the material are affected can be seen by referring to the curves of the drawings.
  • the temperature at which FeRh base alloys normally change from the antiferromagnetic to ferromagnetic state upon heating is approximately 330 K. (57 C.).
  • a severely cold-worked sample consisting of filings of FeRh, starting at the location 10 and following the curve in the directions of the indicating arrows, upon being cooled to slightly less than k. and then heated along the line 11 exhibited no magnetic transition at the temperature where it normally would occur.
  • Upon being heated to about 510 K. Upon being heated to about 510 K., a crystallographic phase change occurred in which the material reverted from the face-centered to the body-centered cubic structure and an abrupt change in magnetization occurred along the line 12.
  • FeRh material processed as outlined above can be further processed to alter the basic character of the transition. Specifically, by further plastically deforming the annealed material in amounts ranging up to about 50 percent reduction, the magnetization change with temperature becomes increasingly linear.
  • curve 25 illustrates the abrupt magnetic transition in a well-annealed FeRh alloy.
  • Curve 26 shows how the transition becomes more gradual when the alloy is cold reduced about 30 percent following the anneal.
  • Curve 27 shows the increased effect of a 50 percent cold reduction. With about 50 percent reduction, the magnetic transition has become virtually linear.
  • the present process provides, for the first time, a method by which a characteristically hard material having unique magnetic properties can be fabricated into plastically deformed shapes and then treated so that it possesses the magnetic properties for which it is valued.
  • a process for producing plastically deformed shapes of iron-rhodium base alloys having the CsCl-type ordered bodycentered cubic structure exhibiting a temperature-dependent abrupt magnetic transition between the antiferromagnetic and the ferromagnetic states comprising hot and cold reducing a starting body of the base alloy to a preselected final dimension using intermediate anneals between cold-reducing stages as required, the cold reduction causing the base alloy to undergo crystallographic transition from the ordered body-centered cubic structure to the disordered face-centered cubic structure, and heat treating the cold reduced alloy shape of final dimension at a temperature no lower than about 235 C. for a time sufiicient to produce the ordered body-centered cubic structure having an abrupt magnetic transition.

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  • Electromagnetism (AREA)
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US615433A 1967-02-13 1967-02-13 Process for producing plastically deformed iron-rhodium base alloy bodies Expired - Lifetime US3637442A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3860458A (en) * 1965-02-26 1975-01-14 Ishifuku Metal Ind Method of making a magnetic body
US5440233A (en) * 1993-04-30 1995-08-08 International Business Machines Corporation Atomic layered materials and temperature control for giant magnetoresistive sensor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10143680C1 (de) * 2001-08-30 2003-05-08 Leibniz Inst Fuer Festkoerper Verfahren zur Herstellung von Metallbändern mit hochgradiger Würfeltextur

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3089795A (en) * 1959-11-18 1963-05-14 Westinghouse Electric Corp Method for producing fiber texture and cube-texture sheets of iron-base alloys
US3144325A (en) * 1962-05-03 1964-08-11 Du Pont Magnetic compositions containing iron, rhodium, and at least one member of the lanthanide series
US3144324A (en) * 1962-05-03 1964-08-11 Du Pont Magnetic compositions containing iron, rhodium, and selected elements from groups ii-, iii-a, iv-a, v-a and vi-a
US3415695A (en) * 1966-04-29 1968-12-10 Gen Electric Process for producing iron-rhodium alloys having improved magnetic transition properties

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3089795A (en) * 1959-11-18 1963-05-14 Westinghouse Electric Corp Method for producing fiber texture and cube-texture sheets of iron-base alloys
US3144325A (en) * 1962-05-03 1964-08-11 Du Pont Magnetic compositions containing iron, rhodium, and at least one member of the lanthanide series
US3144324A (en) * 1962-05-03 1964-08-11 Du Pont Magnetic compositions containing iron, rhodium, and selected elements from groups ii-, iii-a, iv-a, v-a and vi-a
US3415695A (en) * 1966-04-29 1968-12-10 Gen Electric Process for producing iron-rhodium alloys having improved magnetic transition properties

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3860458A (en) * 1965-02-26 1975-01-14 Ishifuku Metal Ind Method of making a magnetic body
US5440233A (en) * 1993-04-30 1995-08-08 International Business Machines Corporation Atomic layered materials and temperature control for giant magnetoresistive sensor

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Publication number Publication date
DE1583983A1 (de) 1970-10-15
FR1554316A (fr) 1969-01-17
GB1172748A (en) 1969-12-03

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