Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates generally to the metal
alloy art and is more particularly concerned with novel
amorphous metal alloys having a unique combination of magnetic
and physical properties, and is further concerned with
ribbons and other useful articles made therefrom.
While it has been recognized by those skilled in the
art that amorphous metals with high saturation magnetization
might be used to advantage in electrical apparatus such as
distribution and power transformers, such alloys are lacking
in necessary ductility and stability for this purpose. Thus,
the iron-rich alloy Fe80B20 has a 4~Msof 15,700-16tlOO
gauss but begins to crystallize within two hours at about
340C and is quite difficult to produce in ductile ribbon
form for electrical machinery apparatus. Other amorphous
~: alloys known heretofore have somewhat greater stability
and adequate ductility for this purpose, but their saturation
magnetization is too low.
This invention based upon our new concepts to be
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described enables avoidance of the prior art necessity of
choosing between desired magnetization and physical properties
in amorphous metals. In other words, it is now possible by
virtue of this invention to provide an amorphous metal in the
form of a ribbon sufficiently ductile to be readily used in
electrical apparatus construction which has good magnetic
properties and elevated temperature stability. Moreover, this
unique combination of properties of special merit in terms of
potential utility of amorphous metals in the general field of
electric power generation, transmission and utilization can
be obtained without incurring any offsetting disadvantage.
- This new result is the consequence of our finding
that saturation magnetization of an amorphous metal alloy is
influenced by the number of electrons available from the glass
former constituents of the alloy. It is also the consequence
of our observation that the stability of such alloys improves
as a greater variety of glass forming atoms are included in
them. Thus, we have found that although dhe btntary alloy
Fe80B20 is difficult to prepare as a high duotilc amorphous
ribbon, small additions of a second glass forming atom may
help formulation of very ductile ribbons under ~ibbon forming
conditions w~ich are otherwise the same.
We have further found that while additlons of
silicon to Fe80B20 reduces 4~M8 because silicon has more
available electrons than boron, the improvement in ductility
is great and the saturation magnetization is only marginally
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diminished. Moreover, stability against crystallization
tendency at elevated temperature is substantially improved in
each instance where boron is substituted in part by silicon
in alloys containing from 80 to 84 atom percent iron. In
such alloys, silicon varies from 1 to 8 atom percent while
boron ranges from 12 to 16 atom percent. Further, in
accordance with the broad, general concept of this invention,
phosphorus~ aluminum, carbon and even sulfur can be used under
certain conditions in combination or individually with silicon
to obtain the new results and advantages stated above.
According to that concept, such use in every instance must
be made without diminishing the alloy iron content below about
80 atom percent. Likewise, the silicon content minimum in
the alloys of this invention is about one atom percent. The
maximum phosphorus and sulfur contents, both individual ~nd
combLned, should not exceed 0.5 atom percent. The penalty for
violating these limits is substantial loss of one or more of
the desired ~agnetic or physical properties.
Briefly described, this invention in its composition
; aepect Insists of an amorphous metal alloy o iron, boron and
silicon having an unique combination of desired physical and
magnetic prop~rties including ductility, elevated temperature
~ . .
stability and saturation flux density by virtue of the fact
that the alloy contains from 80 to 84 atom percent iron, from
12 to 15 atom percent boron and ~rom 1 to 8 atom percent
9 ilicon.
RD-9614
~145161
This invention in its article aspect consists
of the novel alloy defined just above in the form of
a ribbon suitable for use, for example, in the
construction of the magnetoelectric component of
motor, generator, transformer or other electrical
apparatus.
In practicing this invention, novel alloys
defined above and claimed herein are prepared
suitably by mixing together the alloy constituents in the
required proportions in the form of powders and
then melting the mixture to provide molten alloy
for casting to ribbon of the desired dimensions.
Cooling is carried out in the casting operation at a
rate sufficient to produce amorphous material.
~ While variations in melting-point temperatures
between alloys of this invention may impose requirements which
vary with respect to allcy melting and casting operations, the
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preparation and processing of these alloys can be carried
out with uniformly satisfactory results by following
the above procedure and using the described equipment.
In other words, the results of this invention are
reproducible in a substantially routine manner so
long as the compositional limitations stated above
and in the appended claims are strictly observed in
the preparation of the alloys.
Those skilled in the art will gain a
further and better understanding of this invention from
the following illustrative, but not limiting,
examples of the actual practice of the invention and
comparative experiments carried out upon amorphous
metals standing outside the critical limits of compositions
of this invention.
EXAMPLE I
A ribbon of approximately 0.0025 cm thick by
0.13 cm wide of Fe8~B20 alloy was produced by directing
a stream of the alloy onto the surface of a rapidly
revolving chill roll or drum. The amorphous nature of the
resulting ribbon was confirmed by X-ray diffraction,
differential scanning calorimetry and by magnetic and physical
property measurements. The degree of ductility was
determined by measuring the radius of curvature at
which fracture occurred in a simple bend test between
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parallel plates. Ribbon segments were annealed in
purified nitrogen for two hours at temperatures ranging
from 100C to 400C. The crystallization temperature
was taken as that temperature, for the two-hour anneal,
at which the coercive force abruptly increased.
Saturation magnetization and Curie temperature were
obtained by conventional induction techniques as described
in Applied PhYsics, Vol. 29, p. 330, 1976, and Scripta
Met., Vol. 11, p. 367, 1977. The results of these
tests and those conducted on the ribbons produced as
described below in Examples II through VII are set out
in Table I.
EXAMPLE II
A ribbon o Fe40Ni4opl4B6 was prepared and
tested as described in Example I or in the results
set forth in Table I.
EXAMPLE III
~ .
Still another amorphous metal alloy ribbon
of composition Fe40Ni40B20 was prepared and tested
as described in Example I with the results stated in
Table I.
:
;~ EXAMPLE IV
~ ~ A ribbon o~ Fe84 5B15Po 5 was prepared and
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tested as stated in Example I with the results shown
in Table I.
EXAMPLE V
A ribbon oi Fe84B15Sil was prepared and
tested as described in Example I with the results
shown in Table I.
EXAMPLE_VI
Another test ribbon of the physical
specifications of Example I but of composition
Fe80B16Si4 was prepared and tested as to stability
with the result shown in Table I.
r
EXAMP,LE VII
?
Another test ribbon of Fe84B16 was
prepared and tested as to stability with the results
~et out in Table I.
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~: EXAMPLE VIII
Finally~ a ribbon o~ the physical
specifieations of Example I of Fe80B12Si8 was prepared
~: and tested as to stability with the results stated in
Table I.
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TABLE I
!
Yield M
Strain TB ~x ~ R.T. Tc
Alloy ~Y- C C kG C
.
Fe40Ni40P14B60.018 ~100 352 7.9 255
Fe40Ni40B20 0~l8 240~5 358 10,4 396
Fe84B16 ~ - 300 15.6 320
Fe8~ 5B15Po 50.022 245+5 303 15.4 312
84 15 1 0.022 295+5 304 15.4 373 - :
- 80 20 0.021 273+5 343 16.1 382
~ Fe80B16Si4 _ 380 15.~ 390
:; ~ Fe80Bl2si8 ~ - 380 14.9 400 --
x ~ Temperature or initiation of crystallization in 2 hr.
: ~ anneal
s ~ Satura~ion 1ux density
T~ - Curie temperature
t/(2r~-t); ~y i9 the yield strain obtained from the
; value of r at which plastic deformation was first observed.
TB ~ Temperature for initiation of embrittlement ln 2 hr. anneal
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As shown by the tabulated data gathered during these tests,
the temperature at which embrittlement TB occurs is highest
for the ternary composition Fe84B15Sil and the inclusion of
a small amount of phosphorus sharply reduces the embrittlement
temperature. The ductility of the single metalloid alloys is
greater than that of the alloys containing two metalloids, and
e84B15Sil and Fe84.5B15Po 5 are greatest of the test
group. The stability towards embrittlement and towards
crystallization o~ the alloys is at a maximum in the alloys
containing two metalloids and at a minimum in single metalloid
alloys of these series. The saturation magnetization in the
two-metalloid alloys of these series compares favorably with
the maximum value of Fe80B20. Outstanding stability ic
exhibited by the FegOB16Si4 and Fe80 12 8
