NO830120L - AMORPH ALLOYS - Google Patents

Description

The present invention relates to amorphous metal alloys. In particular, the invention relates to jerry-boron-silicon amorphous metals and objects made from them with improved magnetic

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tical properties and physical properties.

Amorphous metals can be produced by rapid solidification of alloys from the molten state to the solid state. Different methods that are known within rapid solidification technology are spin casting and stretch casting, among others. Steam and aemlioerktfre omlyettaislk learv. sAemtnoirnfg e mkean taolglesr å bfrruemkests iflot r veå d freen masv tidllee

The above methods have special properties associated with their non-crystalline structure. Such materials are e.g. known to provide improved mechanical, electrical

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tric, magnetic and acoustic properties compared to corresponding metal alloys with a crystalline structure. In general, the amorphous structure of the metal alloy can be determined

by metallographic techniques or X-ray diffraction. Here, an alloy is considered "amorphous" if the alloy is mainly amorphous, i.e. mint 7 5% amorphous. The best properties are obtained with the (200) x-ray diffraction peak less than one inch above the x-ray background level. This peak occurs at body centered cubic ferrite (hypoeutectic crystalline solid solution}

at a diffraction angle of 106° using Cr^^radiation.

Unless otherwise stated, all compositions given here are atomic percentages.

There are various known alloy compositions such as Fe-B-Si. E.g. is described in US patent 3,856,513 an alloy and foils, bars and powders made from it with the general formula Mb rn U-ynU nY1-, 0^ ~jonU zn (J,± i —I-i dc where M is iron, nickel , chromium, cobalt, vanadium or mixtures thereof, Y is phosphorus, carbon, boron or mixtures thereof and Z is aluminium,

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silicon, tin, antimony, germanium, indium, beryllium or mixtures thereof which can be made essentially amorphous. There are also known mixed alloys of Fe-B-Si which have vis

promising magnetic properties and other properties for better

.effect.-in...electrical--apparatus_such-as-motor-er_and-transforlia-^_

tloergeerri. nUg S mped ateknryt st4a.l2l19is.e3r55 inbgestskemrpiverear tuer n j(derenne -btoemrp-esrialtiusr iuvned which the amorphous metal returns to its crystalline

öptIr:iV:ols. tss0tee0ad n0 nt dGog j) ) e. prenGå n e, mmneei1rnt0 nest leint lgl3si2emr n0°naCgfehnl, oeer teldn iaeskr etoromleiprnergg soeivrpseå iinntmgt et eir bnopst r 8å 0 mo1g ei7n4 ldlirkeemr ke ue /femg nln eer r (c0aaem,tn0.no3

about. 6 atomic percent silicon. An amorphous metal alloy str:Lramel wider.than 2.54 cm and less than 0.00762 cm thick with specific magnetic properties and made from an alloy consisting mainly of 77 to 80% iron,. 12-16% boron and 5 to 10% silicon, all atomic percentages, are described in US patent application no. 2 35.0 64.

Attempts have been made to modify such amorphous materials by adding other elements in order to optimize the mixed alloys for electrical applications. US patent 4lji.217.135 describes an iron-boron-silicon alloy with 1.3

to 2.5 atomic percent carbon to enhance the magnetic properties. US patent 4.19 0.438 describes an iron-boron-silicon

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sium magnetic alloy containing 2-20 atomic percent ruthenium.

Although such mixed alloys have produced relatively good magnetic properties, they are not without weaknesses. All the alloys mentioned above are expensive because they contain

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a relatively large amount of boron. A lower drilling version is very strongly desired. A higher crystallization temperature is also desirable so that the alloys have less tendency to return to the crystalline state. The mixtures should also be close to a eutectic mixture to make casting in the amorphous state easier. Furthermore, the eutectic temperature should be low as possible to improve impactability. It is also desirable that the magnetic saturation should be high, of the order of at least 14000 G. An aim of the present invention is to provide such an alloy that can compete with known conventional nickel-iron alloys

alloys in the trade, such as Al 4750, which numerically consists of 48 wt.% N in pg. 52 wt.% Fe. I _

according to the present invention, an amorphous alloy ring and article is provided which overcomes these problems with the known iron-boron-silicon amorphous metals. An amorphous metal alloy which consists mainly of 73-80% iron, 4-10% bj oIr and 14-17% silicon, (atomic percent) and negligible impurities This alloy is cheaper than any of the other known amorphous alloys, or those in the trade available Fe alloys that the alloy described here is to replace.

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There is provided an article made from the amorphous metal alloy according to the present invention which is at least singularly ductile (as defined herein), and with a core loss that can compete with commercial Ni-Fe alloys such as AL 4750 and in particular a core loss of less than 0.163 watts

per pounds (WPP). at 12.6 kilogauss (1.26 tesla), at 60 Hertz. The object of the alloy has a saturation magnetization measured at 75 ørsted<d>(<B>^^^) of at least 14.0 kilogauss (1.40 tesla) and a coercive force (H c ) of less than 0.045 ørsted, and can available in the form of a thin strip or as a rib material product. The alloy and the resulting product have improved t! e! rmical stability characterized the wood Ocrystallization temperature (Tx> of not less than 49.0 C.

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Fig. 1 shows a . ternary diagram showing the eutectic line 6ig the composition ranges of the present invention.

In general, an amorphous alloy according to the present invention mainly consists of 73-80% iron, 4-10% boron and 14-17% silicon. In fig. 1 are the mixtures that lie within the letter--be/drawn area that delimits the conditions expressed by point-I I E I

tene A,B,C,D and E within the broad range of the present

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invention. The points A, F, G and H express the conditions for the blinds that lie within a preferred range of

fsoom relskigjægrenedr e gojpepnnfoim nnoeg lsest. RLekiknejr a smeg elulotm enpfuor nkbtelnan diNg asJrad fqrholds as defined here, represents the geometric location of eutectic points (lowest melting temperatures) |for the eutectic valley in this area of interest see in the Fe-|B-S:. Referring to the areas of the invention shown in fig. 1 are close enough to the eutectic line or the mold to be essentially amorphous upon impact. The boron content is critical for the alloy's amorphous properties. The higher the boron content, the greater the alloy's tendency to become amorphous. With increased xr content, however, the alloys become deeper. The preferred boron area is from 4% to less than 10% and preferably it is 7% less than 10%. Cheaper alloys with less than 7% boron are part of the invention, but are difficult to cast with good properties. •Silicon in the alloy primarily affects the alloy's thermal stability and to a small extent affects the amorphous properties. Silicon has far less effect on the amorphous properties in the alloy than boron Preferably silicon can vary from more than 15% to 17%..

The alloy according to the present invention is rich in iron. The iron contributes to general magnetic saturation in the alloy and the iron content preferably varies from 73 to 78%.

L! the alloying mixture according to the present invention provides an optimization of the necessary properties of Fej-B-Si alloys for specific electrical applications. One has to give up some properties, but the mixture according to the present invention has been found to be an ideal balance between these properties. It has been found that the iron content must not exceed 80% to give the required magnetic measurement. By keeping the iron content below 80%, other important constituents, namely boron and especially silicon, can be used in increased amounts. In order to obtain an object made from the alloys according to the above invention with increased thermal stability, the amount of silicon is maximized. Larger amounts of silicon raise the crystallisation temperature, enabling heat treatment of tl rimmed materials at higher temperatures without causing crystallization. Heat treatment at higher temperatures is useful -for-- to-reduce-the-internal-stresses-in-the-forward

In stI ilte object, which improves the magnetic properties.

characteristics are maintained for objects made from the alloys.

In the alloy of the present invention, certain insignificant; contaminants or residues be present. Such minor impurities should not in aggregate exceed 0.83 atomic percent: of the alloy. In the following, a tabular list of typical residues that can be tolerated in the alloys according to the present invention is given.

Various known methods for rapid solidification can be used to cast the amorphous metal alloy according to the present invention. In particular, the alloy can be cast using pull casting techniques. A pull casting technique may well involve the continuous delivery of a molten stream or supply of metal through a slotted nozzle located less than 0.035 cm from a casting surface which can be __moved at a speed of approx. 60-3000 m/minute past the nozzle to give an amorphous strip material. The casting surface is usually the outer edge surface of a water-cooled metal wheel produced by e.g. copper. Rapid movement of the casting surface draws a continuous thin layer of the metal from the stock or stem. This layer solidifies quickly at a cooling rate of the order of 1 x 10^°C per second to tape materiai.et. the alloys according to the present invention are preferably cast at a temperature above approx. 1315°C on a casting surface down to ~'ln initial temperature which can vary from approx. 1.6 ten;. 32°C. The BI spirit is cooled to below the solidification temperature and to below the crystallization temperature and after solidification on the ""'casting surface it is separated from this. Such a band may preferably have a width of 2.54 cm or more and a thickness of less than 0.00762 cm and a width-to-thickness ratio of at least 10:1 and preferably at least 250:1. From the alloys according to the present invention, thin strip materials were produced using such a tensile casting technique for the alloy as shown in the following table!. I. L Each t tape was__utg 1ø_de.t _..jL_e,t_JLCL_ø_r_st.ed_DjC_^AgjlJBjLis.k_f_eli OFFSF.T ASM ■ 1982 1 4 hours at 350°C. The amorphous nature of each was confirmed by X-ray diffraction measurements. Further was each ::loved to have. at least singular ductility as determined by a single bending test. Ductility determined by bending tests involves bending the tape across itself in an 180° bend in each direction to determine brittleness. If the band can be bent on itself ;3ely Along a bending line that runs across the band (ie perpendicular to the casting direction). - in a non-recoverable permanent bend without cracking, the tape exhibits ductility. The tape is doubly ductile if it can be bent 180° in both directions without cracking and simple or singularly ductile if it is bent 18 0° only in one direction without cracking. Singular ductility is a minimum requirement for an object made from the alloys according to the present invention. Double ductility is an optimal condition for an object made from the alloy according to the present invention. ""The data in Table II (shown below1) show that the core loss s1/om should be as low as possible in the alloys according to the present invention is still less than the core loss of 0.163 WPP at 12.6 KG (1.26 T) for a commercial alloy AL 4750 which nominally consists of 48% Ni-52% Fe . The AL'475.0 alloy examined was 0.015 cm thick and was manufactured according to recognized manufacturing practices for the alloy. The bands of the alloy according to the present invention were approx. 0.0033 cm thick.

11 The magnetic data for batch no. 158 are in agreement with the other alloy data for the reason that (200). the X-ray diffraction peak is slightly larger than the 2.54 cm above background level set for best properties. Batch 671 of the same mixture was cast a later day when the casting technique was a bit better, which enabled mainly amorphous substance due to the improved casting cooling rate. The properties of batch 158, however, show the alloy's ability to provide magnetic saturation at the required level and useful objects made from it. In comparison, an alloy that lies outside the present invention, Fe^^B^Sj.2q, batch 621, with an extremely high silicon content, fo2~t is largely crystalline and brittle even when it is cast under the best cooling conditions. Because the alloy is not essentially amorphous, it does not develop the desired magnetic properties.

All the batches except ALR 621 are alloys according to the present invention. The data shown in table II are atj. the alloys of the present invention have magnetic saturation properties, coercive force, core loss (in WPP) and apparent core loss (in volt-ampere per pound, VAPP) together*-

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comparable to or better than the AL 4750 alloy.

The present invention provides usable alloys for electrical purposes and objects made from these alloys with good magnetic properties. The alloys ke.n are made less expensive due to the lower raw material costs at Bor. The alloys are amorphous and ductile and have a thermal stability which is greater than for iron-boron-silicon alloys with more than 10 atomic percent boron and less than 14 atomic percent silicon.

Even though several embodiments of the invention are shown and tbaes skmroevdeitfi, as if the device is viærnnee nkfolr arrt amfmo n one of the skilled workers iggtdee t opkpan f irf.onrele-se.

Claims (1)

! ' .1I • il. Amorphous metal alloy, possibly in the form of a strip, characterized by the fact that the alloy consists of 73-80 atomic % iron, 4-10 atomic % boron and 14-17 atomic % iron and more than accidental contamination. i 2. Alloy according to claim 1, containing 4 atomic % to less than 10 atomic % boron. '3. Alloy according to claim 1 or 2 containing more than 15 atomic % to 17 atomic % silicon. <:> 4. Alloy according to claim 3 containing 7 atomic % to less than 10 atomic % boron. IN !5. Alloy according to claim 1, containing 73-78 atomic % iron. i-l 6. Alloy according to claims 1-5, characterized I V; e d that it consists of 73-78 atomic % iron, 7 atomic % to less than 10 atomic % boron and more than 15 atomic % to 17 atomic % silicon. t i 7. Alloy according to claim 1 or 6, characterized in that it does not contain more than 0.83 atom% random impurities. :8. Alloy according to claim 1 or 6, grade is'ert : vlieserd ingesn temfoprerbaetdurr et hvøyaermre estenabn i4 li9t0. O eCt .expressed as a cross.t' ij al-Ii in i i 9. Method for casting the amorphous alloy according to j claims 1^ 8 in the form of a strip with a width of at least 1 2.5 cm, a thickness less than approx. 0.08 mm, a 60 Hertz core | loss of less than 0.3 59 W/kg at 12.6 k gauss, saturation-! j magnetization (B75H )- of at least 14 k gauss and a coercive force <1> of at least 0.045 ørsted and which is at least singularly ductile, characterized by melting an alloy in the essential consisting of 73-80 atomic % iron, -4-10 atomic %1 boron and 14-17 atomic % silicon and which does not contain more than ! <!> in ! random impurities, and perform the molten alloy in shape! i ■ I of one, flow through a slotted nozzle and down onto an over- surface arranged within 0.64 mm of the nozzle, continuously feed the casting surface past the nozzle with one hiasti <g>h et at 60-3050 m/min., allow the casting to at least partially solidify on the casting surface and separating the at least partially solidified casting in the form of a strip from the casting surface. <!> 10. Method according to claim 9, characterized by casting an alloy essentially consisting of 73-78 atomic % iron, 7 atomic % and up to less than 10 atomic % boron and more than 15 atomic % and up to 17 atomic % silicon and not! containing more than random contaminants. j i i i ' r i