US1768237A - Magnetic material - Google Patents

Description

5 Sheets-Sheet 3 Affjz Immune MATERIAL Filed Aug. 5, 5

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WWWWW WWW W P PERMEABILITY 1m 24, 1930. 5, w, ELMEN 1,768,237 namzc IM'BRIAL I 4 Filed Aug. 1925 5 Shoots-Sheet 5 v r I I I r r r r I l I I I r I 1 l 1 I I I I r I 1 r I I I I I I r 1 I 1 I I 1 I 1 r I I I 1 r I I4 by M 4 3 Patented June '2 1930 j "UNITED S TAf-T ES PATENT; dormer:

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ensrar w. or mourn, aw mnsnr, ASSIGNOR 'ro wnsrnan anaemic or maw YORK, N; Y.,

A conromrron on NEW YORK menn ric 1mm.

Application M August 5, 1925.. Serial No. 48,188.

This invention relates to new materials or substances having certain desirable magnetlc qualities, among'which are high magnetic permeability especially at low magnetizing forces,

and low hysteresis and eddy current losses.

- It is the principal object of the invention to providefa magnetic material which will be particularly suitable for use under conditions where'the magnetizing forces are very small,

such as is the case, for example, in the inductive loading of signaling conductors to increasetheir range and speed of operation.

Another object relates to applying this loading material'to a conductive core in a manner to produce a highly eflicient transmission line for long range, Another object is toimprove the electrical and 'magnetic properties of magnetic materials of the type useful for loading signaling conductors and in particular to increase their resistivity with vno-material decrease or an actualincrease of their ermeability at low magnetizing forces an with little increase or with an actual decrease of-their hysteresis losses. These and other objects j will become apparent on consideration of examples of practice thereunder which will be disclosed specifically" in this specification,

with the understanding that the definition of the invention will be. given in the appended claims.

This application is in part a continuation of application. Serial No. 486,009, filed July 20, 1921, now patent 1,586,883, granted une 8 Iron, because of its quality of high mag netic permeability has always been considered indispensable for the cores of tractive electromagnets, for dynamos, motors, telephone receivers, telegraph .relays, etc;

Silicon steel exhibits magnetic qualities superior to ordinary. ironin somev respects, but its employment is limited by its comparative brittleness and the difiiculty of working iron are nickel and cobalt but they are far high speed signaling.

' continuation of my atomic weights and? atomic numbers and in this specification the five elements manganese, 11011, cobalt, nickel and copper, having the consecutive atomic numbers 25, 26, 27, 28 and 29 will be referred to as constituting the mag- .netic group of. elements.

The present invention relates to improvements in magnetic materials of the type useful for application at low magnetizing forces such as are found in the magnetic materials employed in continuous loading of signaling conductors, and similar applications, as distinguished from power apparatus. However, the-invention'has to do generally with new and improvedmagnetic materials and theirutilization. in any commercial application where they. are found useful is within the scope of the invention.

' In my Patent 1,586,884, ranted June 1, 1926 on an application whic' was in part a co nding application, Serial No. 111,080, filed July 24, 1916 there is described indetail an improved magnetic material-consisting of elements of the .so-

called magnetic group, for example, nickel unit. In the Patent No. 1,586,883 previously referred to, there is described and claimed broadly a somewhat similar magnetic material in which a substance is added for the pur pose of increasing resistivity. These magnetic materials are peculiarly suitable for use in the loading of long telegraph cables as it. A good quality of soft iron has'therefore described in a patent to O. E. Buckley 0.

been commonly employed as the best magnetic 1,586,874, granted June 1, 1926.

The claims attached to the present specification are based in part upon certain species ofinvention .divisible from those claimed in '80 Other suitable substances for increasing resistivity of iron-nickel magnetic Without seriously impairing their initial per- 7 force.

ironmickel compositions in and-' scarcity ren er gredlents of magnetic the patents mentioned above and in ,part upon certain newly discovered facts not set forth therein. Prior to applicants researches eventuatin in extensive application of iron-nickel al oys, metals such as chromium, molybdenum, man anese, cobalt and silicon had not been em oyed in magnetic alloys composed of -two e ements of the magnetic group, especiallyof nickel and iron, for their utility. as

rovin or usem applications involving small ma etizing forces. Such materials when com ined with iron and nickel, for example, had been employed for the purpose of making hard steels such as tool steels, anti-corrosive steels, and magnetic bodies of great ma etic retentivity and corrosive It as been discovered, with respect to chromium, whichis claimed broadlyas an ingredient of similar magnetic compositions in Patent 1,586,883, that here is 'a preferred range of chromium content not set forth in said patent. Addition of chromium within this preferred range enhances the beneficial results obtained from its use. It has also been discovered that variation of the chromium content over this preferred range,

the purpose of im' magnetic materials keeping the nickel content and the heat treatment constant, gives a content. For dlfierent heat treatments the maximum initial permeability is at a different chromium content. There is forth for the' first time a body of systematic data upon the magnetic properties of ironnickel-chromium compositions at low magnetizing forces in correlationwith data upon their resistivity. Equivalents for chromium have also been investigated. It has been found thatjmolybdenum, for example, combines with-ironand nickel with resultssimilar-tothose secured in the case of chromium alonafj -For the'purposes of the present specie ficatio'n'. the. chromium group includes the metals chromium, mol bdenum'and tungsten, Uranium is theoretica ly deemed to be a member of the chromium group but for all practical purposes connected with the present invention, it. is excluded from consideration.

meability' are manganese, silicon and cobalt. These elements are noted to be of hi h melting point, that is, above 1150 C. form sohd solutions when combined with amounts within the scope ofjthe present-invention. The so- .:called noble or raremetals are excluded from the scope of this invention even though they have high meltin points, because their cost them unavailable as incompositions: Hence, when reference is made to metals of melting point above 1150 C. it is unders'toodthat resistivity of the alloy.

an extremely high permeabilit full benefit of the maximum range of'in- 1t1a1 permeability around a certain Cl'll'OlIlllllIl here set the loys ey also ruthenium, rhodium, palladium, osmium, iridium' and platinum, as well as uranium, are excluded for the purposes of this specification. v

The present invention relates to a further improvement in this material .and provides a new magnetic material comprising elements of the so-called magnetic group combined in suitable proportions and to which additional material has been added which increases the This alloy when subjected to a proper heat tr'eament' and guarded against undue stresses and other disturbing causes not only'develop's and retains at low magnetizing forces of the order 0 a few tenths of a c. g. s. unit but at the same time has low hysteresis and Furthermore it can-be applied with advantage-to the continuous loading of signaling conductors in such a manner as to obtain the above noted desirable properties.

eddy current losses. f

The invention may be more clearly under- I stood--'"=by reference to the accompanying drawing in which Fig. 1 comprises curves showin the variations in initial permeability of a nickel and iron alloy containing approximately 78 various amounts of the iron content are replaced by equal amounts of a third substance, in this case, chromium.

Fig. 2 shows the variations in maximum permeability under conditions similar to those of Fig. 1.

Fig. 3 is a curve showing the variations in initial permeability of a'magnetic material with variations in the proportions of nickel andiron when a third substance is held at a constant percentage. I Fig. 4 shows the variation in permeability of a preferred composition of this materia com ared with Armco iron and "a high per- -to an alloy of nickeland iron.

Fig. 6 shows-tlir variation in resistivity when'the percentage of chromium is maintained constant andfthe ratio of nickel and iron varied.

Fig. 7 comprises magnetization curves for various compositions of this magnetic material in comparison with similar curves for a high permeability nickel-iron alloy and for Armcoirom f Fig. -8 comprises curves showingthe variations inpermeability with varying magnetic vinduction of the preferred composition as compared with the materials of Fig 7.

Fig. 9 shows half of a hysteresis oop of the improved magnetic mate 'al compared with )dia rammatically.

- the curves n1ckel-iron alloy and Armco iron under similar conditions.

Fig. 10 is an elevation of a conductor loaded with the improved magnetic material of this invention.

Fig. 11 is a cross-s ctional view of the same. a

Fig. 12 is a cross-section of the same conductor when embodied in a submarine cable. Fig. 13 is a sectional view of a type of furnace suitable for annealing the loading conductor. Fig. 14 is anelevation of a conductor wrapped with two'layers of this magnetic materia i Fig.

5 shows a loading coil with its core of this material and its. windings indicated eferrin now more particularly to Fig. 1,

i and B show the effect upon the of a magnetic alloy comel and 21%% iron when of a third substance,'in

initial permeabilitv prising 78 nic varying percentages this case chromium, equal amount of iron, curveA being for one heat treatment and curve B another.

The initial permeability as defined in my copendin'g application referred to above is the permeabilit for zero magnetizing forces. This value is o tained by determining a series of values for exceedingly low forces, say of the order of .01 to .050. g. s. units. The results plot linearl. and may be extrapolated back to the value or H=O, thus giving the g'alue of permeability for zero magnetizing orces.

- The heat treatment for curve A consistedin annealing by slow coolin from 1100 0., followed-by heatingto 600 termined rate, namely, 9.5 per second. In accordance with a slight modification of this heat treatment giving the same results, the material is-first heated to the desired temperature and then cooled slowly to a temperature near' the magnetic transition temperature a and thencooled rapidly at a predetermined rate which is and a rate at which undue stresses and strains Wlllbe set up in the materials. Curve B represents the same conditions as curve A- except that the heat treatment consisted only of the annealing.

The proportions. of 78 72; nickel and 21 iron were selected for preliminary tests since approximately these proportions in initial permeability. When he material reaches a inaximum whenslight -2% cromium by weight is used- ,creases rapidly with larger amountsof amination of this curve itwill the maximum are added to replace an and then coolmg to room temperature at a rapidpredeintermediate an annealing rate,

is given the double heat treatment as represented curve A the initial and'then dechromium. In the case 0 the single heat treatment as shown by-cu'rve B- the maxi'- mum-initial permeability is reached when the material contains approximately 4% chromium by'weight and decreases less rapidly with lar er amounts of chromium.

The e ect upon the maximum "permeabil- Permeability y more than ity of an alloy containing 78 nickel and 21 iron when varyingamounts of the iron are I mium is shown graphically in Fig. 2.- In obtaining the data forcu'rve A the magnetic material was subjected to the same double heat treatment as was used in resented by; curve A of Figfl. From an expermeability decreases very rapidly with an increase of chromium. Thus for an alloy containing 1% chromium there was obtained a maximum permeability of replaced by equal amounts of chrothe test rep- 85. be seen'that 1 150,000, for an alloy containing 2% chromium the maximum permeability was decreased to 60,000 and-for'an alloy containing Y 0 I chromium, the maximum permeability is approximately 10,000. {When the mag-- ne'tic material is subjected to a single heat treatment as illustrated by curve B,the maximum permeability.increases with the chr0- mium content'until a chromlum content of approximately is reached, the maximum permeability then increases rapidly: and

the curve crosses curve A (which relates tothe same composition given the double heat treatment) and remains above the curve A until the chromium content approaches 7%.

As a' result of the discoveries represented by the curves of Figs. land '2 it was seen that an alloy containing approximately 2% chromium, when properly heat treated would be very satisfactory from the standpoint of permeability.

.- In order to obtain a further indicatlon,

then, of the most satisfactory proportions of nickel and iron, thorough tests were made in which the chromium content was maintained constant at- 1.9% and the proportions of nickel and iron varied, The results of these tests which are shown on Fig. 3 indicate that the most satisfactory results are obtained with approximately 78 75 nickel and the balance iron and a third substance of which chromium is the specific example dealt with in the present instance. As indicated by the curve of Fig. 3, the initial permeability curve rises very rapidly as the nickel component approaches 5%, reaching a maximum at approximatel creasing rapi 1y with further increases in the nickel content. These tests were supplemented by tests on other nickel-iron chromium al- /2% nickel and then de-.,

' Y creasing material v and other similar loys containingliup1 to 8% chromium and in -'each casethe g est permeability was obtained when the nickel content was approximately 7 8%%. Similar tests were also made with substances other than chromium. For example, with: small amounts of cobalt, silicon, manganese and molybdenum, as high or higher permeabilities were obtained when the nickel content was approximately 7 8 of the whole as when any other rcentage was used. The expression reslstance 1nwill be used hereinafter to include metals of melting point above 1l50 (3., such for example, as chromium, molybdenum,

common metals and combinations of these elements. The addition of still other elements or substances for the same or other pur' oses, thereby producing compositions within the scope of the appended claims, is not deemed to be a departure from the invention.

In Fig. 4 are curves showing variations in alternating current permeability of various magnetic materials when subjected to a 200 cycle alternating current ma netizing flux of- .001 c. g. s. units and upon which is superimposed varying direct current magnetizin forces. Curve A shows the permeability 0 an alloy containing 7 8 nickel and 2l iron. Curve B shows the improved magnetic material containing 781/ nickel, 1.9% chromium and the blance iron and curve shows the alternating current permeability of a very pure grade of magnetic iron. From these curves it will be seen'that the improved magx netic material containing approximately 2% chromium when subjected to a superimposed direct current magnetizing force within the limits employed in this figure has a considerably higher alternating current permeability than an alloy containing 7 8 mckel and the balanceiron, and has a decidedl hi her A. C. permeability than the best gra e o magnetic iron. The importance of this characteristic of the material is apparent since loaded lines and various kinds of apparatus such as relays,

5 tivityof an alloy telephone receivers and repeating coils are constantly subjected to a greater or lesser direct current magnetizing force upon which is superimposed a varying magnetizing force resulting from voice andsignaling current.

In Fig. 5 is shown the variation-a'fi resiscolltaining' 78%%fnicbl and the balance iron chromiumfior difierent proportions of "the latter two elements.

(It willbe noted that oit the alloy increases rapidly with an' increase in' the of chromium present in the alloy. r

The curve of Fig. .6 shows theyariation in resistiv y of an we mt 's appr x the balance nickel and iron with varying proportions of the latter-two elements. .Asshownbythiseurve the maganese, cobalt and silicon,"

variation in the nickel contentproduces slight change in the resistivity of the material.

The curves shown in Fig. 7 comprise a seriesof magnetization curves for the improv magnetic alloy with-various percentages of chromium in com arisen witha nickel-iron alloy containing 8 nickel and 21%% iron and a very pure grade of magnetic iron. The nickel-iron alloy and the various nickeliron-chromium alloys were 'ven the double heat treatment previously re erred to and the iron sample was heat treated to bring out its best magnetic characteristics. Curve A is the magnetization curve for the nickel-iron alloy containing 78 nickel and. 21 iron. Curve B, which is the improved magnetic material containing 7 8 nickel and approximately 2% rises less rapidly thancurve A except at a point near the origin and saturates at a considerably lower value. Both, however, are far above the curve for Armco iron as represented by curve C which has not even begun to rise steeply at the low magnetizing forces with which we are now chiefly concerned. Curve D is a magnetization curve for a nickeliron alloy containing approximately 7 8 nickel, .98% chromium and the balance iron. Curves E, F and G are for similar alloys containing respectively 2.37%, 3.86% and 6.85% chromium. These curves show that for a given magnetizin force above .025 c. g. 5. units, the permeability is decreased with an increase inthe chromium content. It also may be'seen that the magnetizing force necessary to p oduce maximum permeability increases wit an increase in t e chromium content. Additional tests made with the same samples (not shown in the drawing) indicate that with extremely slow cooling (annealing in the furnace) practically the reverse is true, the permeabihty for a given magnetizing force increasin with increase in the tent an the point of maximum permeability being decreased with. an increase in the amount of chromium present. These tests further show that alloys containing 3% or more of chromium are less sensitive to heat treatment than are those containing less chromium. Therefore, by using alloys containing larger amounts of chromium, it ispossiblgt'o obtain a more uniform product under ordinary commercial process although this uniformity is obtained at a sacrifice of permeability.

The curves of Fig. plotti'n the rmeabi 'ty values of the materials 0 Fig. against the'valies of magnetic induction. 1 Curve A is, the curve for mckelron allo containing 7 8 5% nickel and 21%% 11'011'. urve B is the curve for the chromium with the balancev iron, I

chromium con- 8 are obtained by a material in which approximately 2% of the the curve-{or Armco iron under similar 00nditiom.

- The hysteresiscurves of the three materials of Figs. 7 and 8 are shown in Fig. 9, only the upper half of thecurves being shown.

These curves are carried to a maximum induction of 5,000 0. g. s. units'a-nd are'drawn on the same scale. Curve A is half of the hysteresis loop of the nickel-iron alloy containing 78 nickel and 21 70 iron. Curve. B is a similar curve foran alloy represented by curve A in iron is replaced. by an equal amount of Hchromium and curve C is a similar curve for Armco iron; The hysteresis loop for the imcontaining chromium, while in this particular case slightly less than that of the similar alloy without chromium, is reall I of the same order but both have a very muc smaller area (about than that of the loop of curve C for Armco iron.

I't'will also be noted from a'study of the curves of Fig. 9, that the coercive force of the improved magnetic material, although slightly less, is of the same order as the coermately 2% cive force of the nickel, 21 73 iron, coercive force for iron as represented by curve C. After being subjected to a magnetizing force of 100 c. g. s. units, the coercive force of the nickel-iron alloy containing 7 8 nickel and of the improved magnetic alloy containing approxi chromium is of the order of .05

alloy containing 7 8 5% and is much less than the c. g. s. unit, whereas the coercive force for H terial in its may be fused together in an induction furnace, in the and 78$ of these materials pose, and to this alloy is then added the t ird Armco iron is approximately .86 c. g. s.. unit. In the preparation of this magnetic ma preferred form, iron and nickel proportion of about 19%, iron nickel, good commercial grades being suitable for this ursubstance such as chromium; which increases the res1st1v1ty of the materlal. However, 1n

order to prevent excessive substance from going into amounts of this the slag, it has been found preferable to first make up an alloy of that substance with nickel and then add that alloy to a nickel alloy, so proportioncd as to'give a desired proportion tothe magnetic material when the two alloys are combined. Forcxample, "make a nlckel-lron-chromlum alloy containwhen-it is desired to ng approximately 2%,,chromium, an. alloy I of approximately 75% mium is first pre ared to a molten nic el-iron alloy while in the to the material. After the three nickel and 25% chroand this alloy is added furnace soas to give the desired proportions ingredients Poured in a r are added the.'composition is bar or rod mold and cooled to form a thic which is then rolled, swaged or otherwise A suitable process for making and treating.

.worked into the form in which it is to be used.

the material is disclosed in patent to J H. White, No. 1,586,871, granted June" 1, 1926.

which approximately 2% of the,

the best grade ofmagnetic' tape, the drawing process When the material is to be used for the con-' tinuous loading of signaling conductors, the bar or rod as jected to repeated swaging and annealing operations'or to hot rolling "by which iti's reduced in diameter and correspondin ly elongated. The long rod thus formed is tfien drawn outby repeateddrawing and annealing operations to a size about #20 B and S gage and is then formed'into passing it between flattening rolls and by several such operations flattening it to a tape having a thickness of about a width a little more than .125 inches. In the last annealing operation the material is heated to a temperature of ll00 C. and then allowed to cool slowly thus carrying out the first step of the heat treatment which is not completed until after the tape is wound upon the conductor. This tape is next passed through cutting rolls or discs which trim its edges squarely on both sides and give the tape an exact and uniform width, thus placing it in condition for application upon the conductor. When it is desired to use the loading material in the form of wire, rather than is continued'until the wire has the desired dimensions:

The stranded conductor of F igs'. 10 and 11 comprises a central cylindrical wire 21 enveloped by six surrounds 22, which are shaped annulus about the central wire. It is desirable that the conductor assembled in this way have a smooth cylindrical contour and for this purpose it may be drawn through a die or subjected-to a swa ging operation. The stranded conductor as described has the advantages of flexibility and preservation of conductive continuity in case of breakage of any of the strands by a force not too severe to disrupt all the strands at the same lace. This stranded-conductor 21--22 is. #5 g and S gauge in size and is loaded with the inn-- proved magnetic material in the form of tape as described above. is wrapped helically on the stranded copper core in accordance with my copending appli now Patent No.1,58.6,887-, grante June 1,

I 1926, care being taken to abut the edgesclosely Iwithout overlapping. App

the final step in its h'eat'j treatment and for u'rpose it is drawn lengthwise through this a thin tape by.

.006 inches and The magnetic tape 23 taken from the mold is sublll . aratus for acconi- ""plishing this'is described in detail in patent the f urnace of Fig. 13' which is maintained at a tem erature of about 900 C. This is a mufile *urnac'e with the heating elements 26 betweenthe fire cla' "mu'flie 27 and the fire brick 28. Around t iron outer wall. perlining 30 the e firebrick 28 is a sheet r I The iron tube '29 has a cop inside diameter of which no jects about eightinches beyond thefurnace is about two is a little over. one-half inch. Itextends clear across the furnace The length ofthe pass through the feet and the rate of movement of the conductor therethrough is about three quarters of a foot per minute. the taped wire passes from the furnace and the projected ends of -the air which about normal room temperature, that is, about 20 C. Under the conditions and for the dimensions described, this gives a proper rate of cooling. after heating in the furnace. The conductor should be led awa straight from the furnace for a suflicient distance to ermit it becoming well cooled, since bend- 1 g at this stage may impair its permeability. o the necessary coiling of the taped conductor should be on a large radius not less than two feet, since .the strains involved in coiling and uncoiling on a smaller radious may lower the permeability. After the heat treatment,

walls.

the taped conas' ductor is first insulated in such a manner that the loading material will not be subjected to uneven strains when the cable is submerged at great depths. This is preferably accomplished by coiling the taped conductor with liquid bitumen in accordance with the process described in detail in a copendmg application of Archie 61 ,511, filed February 7 1923, now Patent No. 1,700,766, grante H85 insulated, armoured and mechanically remsubmarine cables by I wrapping of ute and 40 of. different diameter forced according to the usual practice. for I surrounding it with a layer of guttapercha and then with the usual giving the product as shown in cros section in Fig. 12.

-While a certain speed and temperature of 'a certain type of furnace have been described I to produce the desired results inthe case of a particular cable, it is apparent that these factors ma be varied or adjustedtomeet different con 'tions, such for example, as a cable closed:

sions of the conductive core and the width and cross sectionbf' the loading, s cifically for a certain-contemplated examgle of a long gra h transmission; I the r sheath is desired, it may be best to apply it op to directions one outside the other as ing ted i I and the fact that the layers.

furnace at each end and pro-.

rents, but this coating may I thickness or insulating coatings. As may be applied to-the loading material if the tube 29, it cools n. outside of the tubeis kept at low coercivity,

R. Kemp, Serial No.-

eb.5,1929. Itisthena sheath of steel wires,

from the one here dis- 1n A description has been given of -the markably saving of material 10 for-high speed tele-" In somecases where a. .ceiving up ratus. v I

I I coilssmallwiresofthemagthe form of two tapes wound in -the'advantages manner of ing coils.

likely to slip or buckle.

When more than one I coating of oxide on each serves as. an insulating materialfor reducing'the.eddy curajp p s y creased in desired.

With a conductor composed I proved magnetic material containing aproximatel 2% chromium the attenuation osses are ept low since not only does the material have a cause of its hi h resistivity, the eddy losses are also ept at a The improved magnetic material of this inventionis useful for-other purposes than for the continuous loading of signaling conductors; For example, it may be I vantagepusly' in the magnetic circuits of telephone receivers, ringers and electromagnetic devices of various types. Because of its it isof particular importance in the magnetic circuits of moving vane meters,-ma rginal relays, split phase relays, and similar devices in which the sensitivity of operation is influenced to a considerable degree by the'previous magnetic history of the magnetic members. The low saturation point and the shape of the magnetization curves make'this material extremely well adapted for use in the cores of frequency changers and magnetic modulators. teristics are such as :to able material for thelcores of various types of Also, its characof the immake it a very'desir- 100 low hysteresis factor but, becurrent used adtransformers, such, for example,as those used for currents having connectedio the line. 7

on used inthe cores'o which are continuall Another use for'whic it is 'cularly adapted, is as a magnetic shiel for shiel one magnetic fiel ap aratus from extranetransmisslon of music and the voice. Be-

a'wide'fre- (fluency rangesuch as those which occur in t e lump loading'as well. as for continuous loadand low ma small volume made up in rewith a consequent and low cost of manufacture. Coils with coresof this materialjhave magnetic shunts in the core .32 on winch 3 8..and'34 are indicated Chokecoilsj of vergahigh inductance I I the well known y. .Incrderto f been found particularly valuablefor use as submarine telegraph, re-

Such a eoil is'- u'o it isalso-useful for/ magnetic materials this material, it is,

acterized in that t ability even though large currents are superimposed on the loading coil circuit, the core may be provided with gaps filled with nonof the non-magnetic gaps with the windings thereon may be held together by means of clamps 37. i

Although for commercial reasons it'will probably be advantageous'to employ a single element as the substance for increasing the resistivity and the initial permeability of of course, obvious that several elements could be simultaneously employed to obtain one or more of the advantages as set forth in the specification without departing from the spirit of the invention. Iron,'in accordance with this specification,

means iron as described in the literature. of

' prior to August 1, 1925. a What is claimed is: l

, 1. A magnetic composition comprising at least two elements 0 the magnetic group and other metallic substance composed of, metals of melting point above 1150 C. which when added to magnetic compositions composed of such two elements increases the resistivity, characterized in that the proportion of such'other substance is such as not to decrease the initial permeability.

2. A composition in accordance with the foregoing claim, further characterized in that the elements of the magnetic group include nickel and iron. e

3. A composition in accordance with .the second foregoing claim, further character- 1zed in that the elementsof the magnetic group are nickel and iron and the other substance is in a proportion which increases the init-ialpermeability.

4. A magnetic compositionin accordance with the third foregloing claim, further chare elements of the maginitial permeability obtained by the added substance is higher than that of lron.

5. A magnetic compositionin accordance i with-thefourth foregoing claim in which'the "elements of. the magnetic group are nickel and i'ron,'c'haracterized in this that the initial permeability ofthe com ositionwhen heat treated to produce high lnitial permeability is higher than can be produced by heat treatmg. the composition with the othersubstance replaced by iro 6; A magnetic composition of initial pert meability higher than ironcomprising nickel and iron,.the nickel being more than-% of the whole and including other metallic of non-magnetic material and the core sections on each side the whole,

up in the material.

substance of melting point above 11509 C.-

whereby the resistivity of such compositions. is increased. Y V

- 7. A composition in accordance with, the foregoing claim in which the nickel is from to of the composition." j

n 8.". A magnetic material comprising nickel, iron, and a third metallic element of melting pointabove 1150' C. to increase the specific resistancev thereofand in which the nickel component is Whole. I

approximately 78 /2% o fthe 9. A magnetic material comprising nickel, i

and iron to which is added chromium in such amount as with proper treatment will produce higher initial permeability. than when the nickel and iron alone are present.

10. A magnetic. material comprisin'g approximately 7 8 nickel, and the remalnder iron and chromium in such amount as with proper treatment Will produce higher initial permeability than when the chromium is replaced by iron. 1 11. A magnetic material heat treated to have high permeability in a very low range of magnetizing forces comprising nickel,

chromium and iron in which'the nickel com-' ponent consists of approximately 78%% of greater than '7 of the whole and the balance iron. I

12. A magnetic material comprising nickel, chromium and iron in which the nickel component consists of approximately 78 0f the whole, the chromium component not more" than 2%% of the whole and the balance iron. 13. A magnetic material, comprisingta proximately 78 92; nickel, approximate y resistance than if said other element were replaced by iron.

15. A magnetic material complil' ising nickel, iron, and not to exceed 7%-- c nickel component being morethan 70% .ofthe whole,' said magnetic material having those netie group include nickel and iron and, the properties which are produced in such a composition b beingannealedat-a temperature of thei or er'of' 1100 C. and slowly 'eooled" therefrom followed bringing the niate and then" cooling rapidly to a temperature considerably'lower than 600 C. at a ratemthe chromium component not omium, the n termediatean annealing rate and a rate at which undue stresses and will set 16. A magnetic material comprising nickel,

' chromium and iron in which the nickel component comprises approximately 78 of the whole, the chromium component not to exceed 7% of the whole, and the balance iron, :said material having the magnetic'properties which are produced by heatingsuch a compoponent comprises approximately 78 /?r peraturc,

' 78 nickel, ap

pointoi the material.

'- go s. umt.

sition to 1100 heating to 600 point lower C. and slowly cooling, then C. and cooling rapidly to a than the magnetic transition 17 A magnetic material comprising. nickel, chromium and 1 I0I1 in which the mo el comthe whole, the chromium component om 2 to 5% of the whole, and the balance iron, said material having the properties which are produced in such a composltion bein C. an O. and

cooled slowly.

' 18. A magnetic material comprising approximately 7 8 nickel, chromium between about 1% and about 5%, and the balance iron, said magnetic material having the magnetic properties produced in such amaterial byits being heated above a certain temcooled slowly to a temperature near the magnetic transition point for that material, and then cooled rapidly at a rate intermediate an annealing rate and a-rate at which undue stresses and strainswill be set up in thematerial.

19. A I magnetic material comprising a proximately 7 8 'nickel, approximate y 2% chromium," and the balance iron, said magnetic material having the pro rties produced in such a material by its ein heattreated by slowly cooling from 1100 lowedby heating to 600 C., and then cooling rapidly to a transition point of the material. 7 p

20. A magnetic material comprising? nickel, iron and at least one other metallic element of melting point above 1150 C. in an amount not over'10% to give the material increased initial permeability, and

in. inductive relation with said material, means whereby the conductor is caused to carry a current sufiicient to produce in the-material a mag-j netizing force notexceedin'g'a fraction of a balance iron, and in 21. A-magnetic material comprising proximately Bl/ nickel, .approxim 2% chromium, and t combination therewith an electrical oonductorin inductive 'relation' with said material. .22. A loaded conduotorcom ducting 'coreihaving alayer .o'f oading rial wrapped helically .thm&b0ut,"Slld load-.- ing material consisting roximatelyf2% chromium and approximate ISM/ 1ron, th'e loadedconductor being .su jected .to a heat treatment to develop its optimum-ma etic qualities.

23. A magnetic composition comprising.

chiefly two elements'of'the' magnetic grou in lproportions which if used alone woul 't high permeability to be obtained and including additional material group f ol-.

point lowervthan the magnetic sistivilz.

magnetic composition of initial per? in combinationtherewith an electrical conductor meability more constant rising FE Cone of approximatelymit high maximum rmeability to be obtained and inclu additional material selected from the metallic elements of melting point above 1150 C. whereby thetinitial permeabilit is increased and the maximum permeability is not increased as compared with the same two elements of the magnetic in the same proportions without the additional material.

25. A magnetic composition of initial per meability over 200 containing between 64% and 85% nickel and the balance chiefly iron plus an amount upto 8% of resistance increasing material selected from metals of melting point over 1150 C.

26. meability over 200 in whichnickel is present in an amount between 64% of the nickel-iron content and 85% of the entire and the balance chiefly iron plus an amount up to 8% of materialof the c romium oup o' the'periodic table for increasing e re- 27 meability over 200 m which nickel is present in an amount between 64% content and 85% of the entire-composition, in which chromium is resent in an amount from'1% to 8% and t e balance is chiefly iron. r r

28. A magnetic com 'tion'ofinitial permeability over 200 comprising nickel and iron in proportions in which the nickel comprises from 64% of the nickel-ir content'to 85% of the whole and additiona material selected from the group of metals having a melting point above'1150 'for the peradditional material. I 29. A magnetic composition of initial permeability-"over 200 comprising nickel and ironin proportions in which the nickel-compri 'fm 6 t0' 85% of the whole up to of the whole selected from the group of metals having a melting point above 1150 C. and forming a nickel-iron 'compounds mounts under 10% for reducing the byline: sis loss and increasing the constancy. 91181,- meability.

magnet1c composition of initial per-.

composition solid solution with when present -:in'

selected from the metallic elements of meltof thenickel-ironwithouttbe of the nickel-iron content 1 and additional material 30. A composition in accordance with the foregoing claim in which said additional material is composed mium cup of the periodic table.

31. magnetic material com 2% chromium, 64% .to 85% nickel and the balance chiefly iron.

32. A magnetic composition heat treated to develop desirable magnetic properties at low magnetizing forces'comprising chiefly nickel and iron in which the nickel lies between 65% of the total iron-nickel content and 85% of the whole, characterized in that from to 10% of: the entire composition is composed of material selected from the group of elements including chromium, molybdenum, cobalt, silicon and manganese.

' In witness whereof, I hereunto subscribe my name this 1st day of August, A. D. 1925.

- GUSTAEW; ELMEN.

of elements of the chro-,

rising about

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