U.S. patent number 3,830,635 [Application Number 05/161,324] was granted by the patent office on 1974-08-20 for aluminum nickel alloy electrical conductor and method for making same.
This patent grant is currently assigned to Southwire Company. Invention is credited to Enrique C. Chia, Roger J. Schoerner.
United States Patent |
3,830,635 |
Chia , et al. |
* August 20, 1974 |
ALUMINUM NICKEL ALLOY ELECTRICAL CONDUCTOR AND METHOD FOR MAKING
SAME
Abstract
Aluminum alloy electrical conductors are produced from aluminum
base alloys containing from about 0.20 percent to about 1.60
percent by weight nickel, from about 0.30 percent to about 1.30
percent by weight cobalt, optionally up to about 2.00 percent by
weight of additional alloying elements, and from about 97.00
percent to about 99.50 percent by weight aluminum. The alloy
conductors have an electrical conductivity of at least 57 percent,
based on the International Annealed Copper Standard (IACS), and
improved properties of increased thermal stability, tensile
strength, percent ultimate elongation, ductility, fatigue
resistance and yield strength as compared to conventional aluminum
alloys of similar electrical properties.
Inventors: |
Chia; Enrique C. (Carrollton,
GA), Schoerner; Roger J. (Carrollton, GA) |
Assignee: |
Southwire Company (Carrollton,
GA)
|
[*] Notice: |
The portion of the term of this patent
subsequent to April 30, 1991 has been disclaimed. |
Family
ID: |
26844676 |
Appl.
No.: |
05/161,324 |
Filed: |
July 9, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
147196 |
May 26, 1971 |
|
|
|
|
Current U.S.
Class: |
420/537; 148/437;
420/542; 420/551; 29/527.7; 164/463; 420/550 |
Current CPC
Class: |
H01B
1/023 (20130101); C22C 21/00 (20130101); Y10T
29/49991 (20150115) |
Current International
Class: |
H01B
1/02 (20060101); C22C 21/00 (20060101); B21c
001/00 (); C22f 001/04 () |
Field of
Search: |
;75/138,139,148,147,146,140,141,142,143,144 ;164/76
;148/32,32.5,2,11.5A ;29/193,527.7 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dean; R.
Attorney, Agent or Firm: Wilks; Van C. Hanegan; Herbert
M.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of our copending
application Ser. No. 147,196, filed May 26, 1971, now abandoned.
Claims
What is claimed is:
1. An aluminum alloy electrical conductor having a minimum
conductivity of 57 percent IACS consisting essentially of from
about 0.20 weight percent to about 1.60 weight percent nickel, from
about 0.30 weight percent to about 1.30 weight percent cobalt, the
remainder being aluminum with associated trace elements.
2. The aluminum alloy electrical conductor of claim 1, further
including an additional alloying element selected from the group
consisting of magnesium and iron, in an amount ranging from 0.001
weight percent to 1.0 weight percent.
3. The aluminum alloy electrical conductor of claim 1, further
including iron as an additional alloying element in an amount
ranging from about 0.1 percent to about 0.5 percent.
4. The aluminum alloy electrical conductor of claim 1, further
including magnesium as an additional alloying element in an amount
ranging from about 0.1 percent to about 0.5 percent.
5. The aluminum alloy electrical conductor according to claim 1
wherein the weight percentages of the constituents are as
follows:
6. The aluminum alloy conductor according to claim 1 wherein the
weight percentages of the constituents are as follows:
7. The aluminum alloy electrical conductor according to claim 1,
wherein the weight percentages of the constituents are as
follows:
8. The aluminum alloy electrical conductor according to claim 1
wherein the weight percentages of the constituents are as
follows:
9. The aluminum alloy electrical conductor according to claim 1
wherein the weight percentages of the constituents are as
follows:
10. The aluminum alloy electrical conductor according to claim 1
wherein the weight percentages of the constituents are as
follows:
11. The aluminum alloy electrical conductor of claim 1 wherein said
conductor is in the form of a rod.
12. The aluminum alloy electrical conductor according to claim 1
wherein said conductor is in the form of a wire.
13. An aluminum alloy electrical conductor having a minimum
conductivity of 57 percent IACS consisting essentially of from
about 0.20 weight percent to about 1.60 weight percent nickel, from
about 0.30 weight percent to about 1.30 weight percent cobalt, the
remainder being aluminum with associated trace elements, said
aluminum alloy electrical conductor having the following properties
when measured as a No. 10 A.W.G. fully annealed wire:
14. The method of preparing an aluminum alloy conductor having a
minimum conductivity of at least 57% IACS comprising the steps
of:
A. alloying from about 0.20 weight percent to about 1.60 weight
percent nickel, from about 0.30 to about 1.30 weight percent
cobalt, the remainder being aluminum with associated trace
elements;
B. casting the alloy in a moving mold formed between a groove in
the periphery of a rotating casting wheel and a metal belt lying
adjacent said groove for a portion of its length;
C. hot rolling the cast alloy substantially immediately after
casting while the cast alloy is in substantially that condition as
cast to form a continuous rod;
said aluminum alloy conductor having the following properties when
measured as a fully annealed wire:
Tensile strength: at least 12,000 psi
Yield strength: at least 8,000 psi.
15. The method according to claim 14 including the further step of
drawing said conductor through wire-drawing dies, without annealing
the conductor between drawing dies, to form wire.
16. The method according to claim 14 wherein the alloying step also
includes the addition of alloying elements taken from the group
consisting of iron and magnesium, in an amount ranging from 0.001
to 1.0 percent, by weight.
17. The method according to claim 14 wherein the alloying step
includes the addition of iron as an alloying element in an amount
ranging from about 0.1 percent to about 0.5 percent, by weight.
18. The method according to claim 14 wherein the alloying step
includes the addition of magnesium as an alloying element in an
amount ranging from about 0.1 percent to about 0.5 percent, by
weight.
19. The method according to claim 14 wherein the alloying step
includes the addition of magnesium in an amount sufficient to yield
an alloy having the following weight percentages:
20. The method according to claim 14 wherein the alloying step
includes the addition of iron in an amount sufficient to yield an
alloy having the following weight percentages:
21. The method according to claim 14 wherein the alloying step
includes the addition of misch metal in an amount sufficient to
yield an alloy having the following weight percentages:
22. The method according to claim 14 wherein the alloying step
includes the addition of niobium and tantalum in an amount
sufficient to yield an alloy having the following weight
percentages:
23. The method according to claim 14 wherein the alloying step
includes the addition of copper and silicon in an amount sufficient
to yield an alloy having the following weight percentages:
24. The method according to claim 14 wherein the alloying step
includes the addition of zirconium in an amount sufficient to yield
an alloy having the following weight percentages:
25. The method according to claim 14 including the further step
of:
D. drawing the rod through wire-drawing dies, without annealing the
rod between drawing dies, to form wire; said wire having the
following properties when measured as a No. 10 A.W.G. fully
annealed wire:
Description
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention concerns an aluminum base alloy especially
suited for producing high strength light weight electrical
conductors including wire, rod and other such articles of
manufacture. The present alloy is particularly well suited for use
as a wire, rod, cable, bus bar, tube connector, termination,
receptacle plug, or electrical contact device for conducting
electricity.
Aluminum base alloys are finding wider acceptance in the
marketplace of today because of their light weight and low cost.
One area where aluminum alloys have found increasing acceptance is
in the replacement of copper in the manufacture of electrically
conductive wire. Conventional electrically conductive aluminum
alloy wire (referred to as EC) contains a substantial amount of
pure aluminum and trace amounts of impurities such as silicon,
vanadium, iron, copper, manganese, magnesium, zinc, boron and
titanium.
Even though desirable in terms of weight and cost, aluminum alloys
have received far less than complete acceptance in the electrical
conductor marketplace. One of the chief reasons for the lack of
complete acceptance is the range of physical properties available
with conventional EC aluminum alloy conductors. If the physical
properties, such as thermal stability, tensile strength, percent
elongation, ductility and yield strength, could be improved
significantly without substantially lessening the electrical
conductivity of the finished product, a very desirable improvement
would be achieved. It is accepted, however, that addition of
alloying elements, as in other aluminum alloys, reduces
conductivity while improving the physical properties. Consequently,
only those additions of elements which improve physical properties
without substantially lessening conductivity will yield an
acceptable and useful product.
It is an object of the present invention, therefore, to provide a
new aluminum alloy electrical conductor which combines improved
physical properties with acceptable electrical conductivity. These
and other objects, features and advantages of the present invention
will be apparent from a consideration of the following detailed
description of an embodiment of the invention.
In accordance with the invention, the present aluminum base alloy
is prepared by mixing nickel, cobalt and optionally other alloying
elements with aluminum in a furnace to obtain a melt having
requisite percentages of elements. It has been found that suitable
results are obtained with nickel present in a weight percentage of
from about 0.20 percent to about 1.60 percent. Superior results are
achieved when nickel is present in a weight percentage of from
about 0.50 percent to about 1.00 percent and particularly superior
and preferred results are obtained when nickel is present in a
percentage by weight of from about 0.60 percent to about 0.80
percent.
Suitable results are obtained with cobalt present in a weight
percentage of from about 0.30 percent to about 1.30 percent.
Superior results are achieved when cobalt is present in a weight
percentage of from about 0.40 percent to about 0.80 percent and
particularly superior and preferred results are obtained when
cobalt is present in a percentage by weight of from about 0.45
percent to about 0.65 percent.
The aluminum content of the present alloy may vary from about 97.00
percent to about 99.50 percent by weight with superior results
being obtained when the aluminum content varies between about 97.80
percent and about 99.20 percent by weight. Since the percentages
for maximum and minimum aluminum do not correspond with the
maximums and minimums for alloying elements, it should be apparent
that suitable results are not obtained if the maximum percentages
for all alloying elements are employed. If commercial aluminum is
employed in preparing the present melt, it is preferred that the
aluminum, prior to adding to the melt in the furnace, contain no
more than about 0.10 percent total of trace impurities.
Optionally the present alloy may contain an additional alloying
element of group or alloying elements. The total concentration of
the optional alloying elements may be up to about 2.00 percent by
weight; preferably from about 0.10 percent to about 1.50 percent by
weight is employed. Particularly superior and preferred results are
obtained when from about 0.10 percent to about 1.00 percent by
weight of total additional alloying elements is employed.
Additional alloying elements include the following:
ADDITIONAL ALLOYING ELEMENTS ______________________________________
Magnesium Scandium Terbium Iron Thorium Erbium Copper Tin Neodymium
Silicon Molybdenum Indium Zirconium Zinc Boron Cerium Tungsten
Thallium Niobium Chromium Rubidium Hafnium Bismuth Titanium
Lanthanum Antimony Carbon Tantalum Vanadium Cesium Rhenium Yttrium
Dysprosium ______________________________________
Superior results are obtained with the following additional
alloying elements in the percentages, by weight, as shown:
PREFERRED ADDITIONAL ALLOYING ELEMENTS
______________________________________ Magnesium 0.001 to 1.00%
Iron 0.001 to 1.00% Copper 0.05 to 1.00% Silicon 0.05 to 1.00%
Zirconium 0.01 to 1.00% Niobium 0.01 to 2.00% Tantalum 0.01 to
2.00% Yttrium 0.01 to 1.00% Scandium 0.01 to 1.00% Thorium 0.01 to
1.00% Rare Earth Metals 0.01 to 2.00% Carbon 0.01 to 1.00%
______________________________________
Particularly superior and preferred results are obtained with the
use of iron or magnesium as the additional alloying element.
Suitable results are obtained with magnesium or iron in a
percentage range of from about 0.001 to about 1.00 percent by
weight with superior results being obtained when from about 0.025
percent to about 0.50 percent by weight is used. Particularly
superior and preferred results are obtained when from about 0.03 to
about 0.10 percent by weight of magnesium or iron is employed.
The rare earth metals may be present either individually within the
percentage range stated or as a partial or total group, the total
percentage of the group being within the percentage range stated
previously.
It should be understood that the additional alloying elements may
be present either individually or as a group of two or more of the
elements. It should be understood, however, that if two or more of
the additional alloying elements are employed, the total
concentration of additional alloying elements should not exceed
about 2.00 percent by weight.
After preparing the melt, the aluminum alloy is preferably
continuously cast into a continuous bar by a continuous casting
machine and then, substantially immediately thereafter, hot-worked
in a rolling mill to yield a continuous aluminum alloy rod.
One example of a continuous casting and rolling operation capable
of producing continuous rod as specified in this application is
contained in the following paragraphs. It should be understood that
other methods of preparation may be employed to obtain suitable
results but that preferable results are obtained with continuous
processing. Such other methods include conventional extrusion and
hydrostatic extrusion to obtain rod or wire directly, sintering an
aluminum alloy powder to obtain rod or wire directly, casting rod
or wire directly from a molten aluminum alloy, and conventional
casting of aluminum alloy billets which are subsequently hot-worked
to rod and drawn with intermediate anneals into wire.
CONTINUOUS CASTING AND ROLLING OPERATION
A continuous casting machine serves as a means for solidifying the
molten aluminum alloy metal to provide a cast bar that is conveyed
in substantially the condition in which it solidifed from the
continuous casting machine to the rolling mill, which serves as a
means for hot-forming the cast bar into rod or another hot-formed
product in a manner which imparts substantial movement to the cast
bar along a plurality of angularly disposed axes.
The continuous casting machine is of conventional casting wheel
type having a casting wheel with a casting groove in its periphery
which is partially closed by an endless belt supported by the
casting wheel and an idler pulley. The casting wheel and the
endless belt cooperate to provide a mold into one end of which
molten metal is poured to solidify and from the other end of which
the cast bar is emitted in substantially that condition in which it
solidified.
The rolling mill is of conventional type having a plurality of roll
stands arranged to hot-form the cast bar by a series of
deformations. The continuous casting machine and the rolling mill
are positioned relative to each other so that the cast bar enters
the rolling mill substantially immediately after solidification and
in substantially that condition in which it solidified. In this
condition, the cast bar is at a hot-forming temperature within the
range of temperatures for hot-forming the cast bar at the
initiation of hot-forming without heating between the casting
machine and the rolling mill. In the event that it is desired to
closely control the hot-forming temperature of the cast bar within
the conventional range of hot-forming temperatures, means for
adjusting the temperature of the cast bar may be placed between the
continuous casting machine and the rolling mill without departing
from the inventive concept disclosed herein.
The roll stands each include a plurality of rolls which engage the
cast bar. The rolls of each roll stand may be two or more in number
and arranged diametrically opposite from one another or arranged at
equally spaced positions about the axis of movement of the cast bar
through the rolling mill. The rolls of each roll stand of the
rolling mill are rotated at a predetermined speed by a power means
such as one or more electric motors and the casting wheel is
rotated at a speed generally determined by its operating
characteristics. The rolling mill serves to hot-form the cast bar
into a rod of a cross-sectional area substantially less than that
of the cast bar as it enters the rolling mill.
The peripheral surfaces of the rolls of adjacent roll stands in the
rolling mill change in configuration; that is, the cast bar is
engaged by the rolls of successive roll stands with surfaces of
varying configuration, and from different directions. This varying
surface engagement of the cast bar in the roll stands functions to
knead or shape the metal in the cast bar in such a manner that it
is worked at each roll stand and also to simultaneously reduce and
change the cross-sectional area of the cast bar into that of the
rod.
As each roll stand engages the cast bar, it is desirable that the
cast bar be received with sufficient volume per unit of time at the
roll stand for the cast bar to generally fill the space defined by
the rolls of the roll stand so that the rolls will be effective to
work the metal in the cast bar. However, it is also desirable that
the space defined by the rolls of each roll stand not be overfilled
so that the cast bar will not be forced into the gaps between the
rolls. Thus, it is desirable that the rod be fed toward each roll
stand at a volume per unit of time which is sufficient to fill, but
not overfill, the space defined by the rolls of the roll stand.
As the cast bar is received from the continuous casting machine, it
usually has one large flat surface corresponding to the surface of
the endless band and inwardly tapered side surfaces corresponding
to the shape of the groove in the casting wheel. As the cast bar is
compressed by the rolls of the roll stands, the cast bar is
deformed so that it generally takes the cross-sectional shape
defined by the adjacent peripheries of the rolls of each roll
stand.
Thus, it will be understood that with this apparatus, cast aluminum
alloy rod of an infinite number of different lengths is prepared by
simultaneous casting of the molten aluminum alloy and hot-forming
or rolling the cast aluminum bar. The continuous rod has a minimum
electrical conductivity of 57 IACS and may be used in conducting
electricity or it may be drawn to wire of a smaller cross-sectional
diameter.
To produce wire of various gauges, the continuous rod produced by
the casting and rolling operation is processed in a reduction
operation. The unannealed rod (i.e., as rolled to f temper) is
cold-drawn through a series of progressively constricted dies,
without intermediate anneals, to form a continuous wire of desired
diameter. It has been found that the elimination of intermediate
anneals is preferable during the processing of the rod and improves
the physical properties of the wire. Processing with intermediate
anneals is acceptable when the requirements for physical properties
of the wire permit reduced values. The conductivity of the
hard-drawn wire is at least 58 percent IACS. If greater
conductivity or increased elongation is desired, the wire may be
annealed or partially annealed after the desired wire size is
obtained and cooled. Fully annealed wire has a conductivity of at
least 59 IACS. At the conclusion of the drawing operation and
optional annealing operation, it is found that the alloy wire has
the properties of improved tensile strength and yield strength
together with improved thermal stability, percent ultimate
elongation and increased ductility and fatigue resistance as
specified previously in this application. The annealing operation
may be continuous as in resistance annealing, induction annealing,
convection annealing by continuous furnaces or radiation annealing
by continuous furnaces, or, preferably, may be batch annealed in a
batch furnace. When continuously annealing, temperatures of about
450.degree.F to about 1,200.degree.F may be employed with annealing
times of about 5 minutes to about 1/10,000 of a minute. Generally,
however, continuous annealing temperatures and times may be
adjusted to meet the requirements of the particular overall
processing operation so long as the desired physical properties are
achieved. In a batch annealing operation, a temperature of
approximately 400.degree.F to about 750.degree.F is employed with
residence times of about 30 minutes to about 24 hours. As mentioned
with respect to continuous annealing, in batch annealing the times
and temperatures may be varied to suit the overall process so long
as the desired physical properties are obtained.
It has been found that the properties of a Number 10 gauge
(American wire gauge) fully annealed soft wire of the present alloy
vary between the following figures:
Tensile % Yield Conductivity Strength, psi. Elongation Strength,
psi. ______________________________________ 58%-63+% 12,000-24,000
12%-30% 8,000-18,000 ______________________________________
A more complete understanding of the invention will be obtained
from the following examples:
EXAMPLE 1
Various melts were prepared by adding the required amount of
alloying elements to 1,816 grams of molten aluminum, containing
less than 0.10 percent trace element impurities, to achieve a
percentage concentration of elements as shown in the accompanying
table; the remainder being aluminum. Graphite crucibles were used
except in those cases where the alloying elements were known
carbide formers, in which cases aluminum oxide crucibles were used.
The melts were held for sufficient times and at sufficient
temperatures to allow complete solubility of the alloying elements
with the base aluminum. An argon atmosphere was provided over the
melt to prevent oxidation. Each melt was continuously cast on a
continuous casting machine and immediately hot-rolled through a
rolling mill to 3/8 inch continuous rod. Wire was then drawn and
annealed from the rod (soft [annealed] wire from hard [as rolled]
rod). The final wire diameter obtained was 0.1019 inches, 10 gauge
AWG.
The types of alloys employed and the results of the tests performed
thereon are as follows:
Ni Fe Mg Co UTS %Elong %IACS 0.80 0.08 0.80 18,900 25.6 60.06 0.30
0.10 0.90 19,040 22.0 59.75 0.40 0.80 0.10 0.40 19,400 23.3 60.65
%Elong. = Percent ultimate elongation UTS = Ultimate Tensile
Strength %IACS = Conductivity in Percentage IACS
EXAMPLE 2
An additional alloy melt was prepared according to Example 1 having
a composition as follows in weight percent:
Nickel -- 0.60% Cobalt -- 0.60% Magnesium -- 0.07% Aluminum --
Remainder
The melt was processed to a No. 10 gauge soft wire. The physical
properties of the wire were as follows:
Ultimate Tensile Strength -- 18,800 psi Percent Ultimate Elongation
-- 21% Conductivity -- 59.05% IACS
EXAMPLE 3
An additional alloy melt was prepared according to Example 1 having
a composition as follows in weight percent:
Nickel -- 0.80% Cobalt -- 0.50% Misch Metal -- 1.0% Aluminum --
Remainder
Misch metal is a commercial designation for a blend of rare earth
metals and Thorium obtained during the processing of Thorium
metal.
The melt was processed to a No. 10 gauge soft wire. The physical
properties of the wire were as follows:
Ultimate Tensile Strength -- 18,500 psi Percent Ultimate Elongation
-- 19% Conductivity -- 59.2% IACS
EXAMPLE 4
An additional alloy melt was prepared according to Example 1 having
a composition as follows in weight percent:
Nickel -- 0.80% Cobalt -- 0.40% Niobium -- 0.20% Tantalum -- 0.20%
Aluminum -- Remainder
The melt was processed to a No. 10 gauge soft wire. The physical
properties of the wire were as follows:
Ultimate Tensile Strength -- 19,880 psi Percent Ultimate Elongation
-- 19.6% Conductivity -- 59.3% IACS
EXAMPLE 5
An additional alloy melt was prepared according to Example 1 having
a composition as follows in weight percent:
Nickel -- 0.60% Cobalt -- 0.35% Copper -- 0.20% Silicon -- 0.18%
Aluminum -- Remainder
The melt was processed to a No. 10 gauge soft wire. The physical
properties of the wire were as follows:
Ultimate Tensile Strength -- 18,000 psi Percent Ultimate Elongation
-- 19.3% Conductivity -- 59.5% IACS
EXAMPLE 6
An additional alloy melt was prepared according to Example 1 having
a composition as follows in weight percent:
Nickel -- 0.80% Cobalt -- 0.45% Zirconium -- 0.30% Aluminum --
Remainder
The melt was processed to a No. 10 gauge soft wire. The physical
properties of the wire were as follows:
Ultimate Tensile Strength -- 18,900 psi Percent Ultimate Elongation
-- 18.8% Conductivity -- 59.9% IACS
EXAMPLE 7
Various melts were prepared by adding the required amount of
alloying elements to 1,816 grams of molten aluminum, containing
less than 0.10 percent trace element impurities, to achieve a
percentage concentration of elements as shown in the accompanying
table; the remainder being aluminum. Graphite crucibles were used
except in those cases where the alloying elements were known
carbide formers, in which cases aluminum oxide crucibles were used.
The melts were held for sufficient times and at sufficient
temperatures to allow complete solubility of the alloying elements
with the base aluminum. An argon atmosphere was provided over the
melt to prevent oxidation. Each melt was continuously cast on a
continuous casting machine and immediately hot-rolled through a
rolling mill to 3/8 inch continuous rod. Wire was then drawn and
annealed from the rod which had been annealed for five hours at
650.degree.F (soft [annealed] wire from soft [annealed] rod). The
final wire diameter obtained was 0.1019 inches, 10 gauge AWG.
The types of alloys employed and the results of the tests performed
thereon are as follows:
TABLE I ______________________________________ Ni Fe Mg Co UTS
%Elong. %IACS 0.80 0.08 0.80 16,500 26.2 61.10 0.30 0.10 0.90
16,850 24.3 60.40 0.40 0.80 0.10 0.40 17,100 25.0 60.90
______________________________________
ADDITIONAL EXAMPLES
Additional alloy melts were prepared according to Example 1. The
composition and the physical properties of No. 10 gauge soft wire
of the alloy melts were as follows:
TABLE 2
__________________________________________________________________________
% % IACS Example Ni Co Mg UTS in psi Elongation Conductivity
__________________________________________________________________________
8 0.2 0.6 18,900 26.9 60.55 9 0.2 0.8 18,600 22.8 61.23 10 0.8 0.6
0.1 17,800 23.0 60.50
__________________________________________________________________________
Through testing and analysis of an alloy containing 0.80 weight
percent nickel, 0.30 weight percent cobalt, and the remainder
aluminum, it has been found that the present aluminum base alloy
after cold working includes an intermetallic compound precipitate.
The compound is identified as nickel aluminate (NiAl.sub.3). The
nickel intermetallic compound is found to be very stable and
expecially so at high temperatures. The compound also has a low
tendency to coalesce during annealing of products formed from the
alloy and the compound is generally incoherent with the aluminum
matrix. The mechanism of strengthening for this alloy is in part
due to the dispersion of the nickel intermetallic compound as a
precipitate throughout the aluminum matrix. The precipitate tends
to pin dislocation sites which are created during cold working of
the wire formed from the alloy. Upon examination of the nickel
intermetallic compound precipitate in a cold drawn wire, it is
found that the precipitates are oriented in the direction of
drawing. In addition, it is found that the precipitates can be
spherical, rod-like or plate-like in configuration and a majority
are less than 2 microns in length and less than one-half micron in
width.
Other intermetallic compounds may also be formed depending upon the
constituents of the melt and the relative concentrations of the
alloying elements. Those intermetallic compounds include the
following: Ni.sub.2 Al.sub.3, MgCoAl, Co.sub.2 Al.sub.9, Co.sub.4
Al.sub.13, Fe.sub.2 Al.sub.5, FeAl.sub.3, CeAl.sub.4, CeAl.sub.2,
VAl.sub.11, VAl.sub.7, VAl.sub.6, VAl.sub.3, VAl.sub.12, Zr.sub.3
Al, LaAl.sub.4, LaAl.sub.2, FeNiAl.sub.10, Co.sub.2 Al.sub.5,
FeNiAl.sub.9, Zr.sub.2 Al.
A characteristic of high conductivity aluminum alloy wires which is
not indicated by the historical tests for tensile strength, percent
elongation and electrical conductivity is the possible change in
properties as a result of increases, decreases or fluctuations of
the temperature of the strands. It is apparent that the maximum
operating temperature of a strand or series of strands will be
affected by this temperature characteristic. The characteristic is
also quite significant from a manufacturing viewpoint since many
insulation processes require high temperature thermal cures. In
tests which determine the decrease in tensile and yield strength in
response to aging at established temperatures and times the
aluminum alloy wire of the present invention has been found to have
the characteristic of high thermal stability.
A significant aspect shown by the results of these tests is the
lack of thermal stability obtainable with several aluminum alloys.
The test sample wire identified as No. 2 and 3 show a significant
decrease in thermal stability in the yield and tensile strength
tests and alloy No. 2 has almost completely softened after a 550
hour soak period at 190.degree.-200.degree.C. On the other hand,
the wire fabricated from the present alloy demonstrates a high
degree of thermal stability by exhibiting zero decreases in yield
and tensile strength.
For the purpose of clarity, the following terminology used in this
application is explained as follows:
Aluminum alloy rod -- A solid product that is long in relation to
its cross-section. Rod normally has a cross-section of between 3
inches and 0.375 inches.
Aluminum alloy wire -- A solid wrought product that is long in
relation to its cross-section, which is square or rectangular with
sharp or rounded corners or edges, or is round, a regular hexagon
or a regular octagon, and whose diameter or greatest perpendicular
distance between parallel faces is between 0.374 inches and 0.0031
inches.
While this invention has been described in detail with particular
reference to preferred embodiments thereof, it will be understood
that variations and modifications can be effected within the spirit
and scope of the invention as described hereinbefore and as defined
in the appended claims.
* * * * *