CA1155687A - Alloys - Google Patents
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- CA1155687A CA1155687A CA000379815A CA379815A CA1155687A CA 1155687 A CA1155687 A CA 1155687A CA 000379815 A CA000379815 A CA 000379815A CA 379815 A CA379815 A CA 379815A CA 1155687 A CA1155687 A CA 1155687A
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Abstract
ABSTRACT
An alloy of copper, aluminium and manganese falling within the area on a ternary diagram defined by the points: ABCDEF.
An alloy having a .beta.-brass type construction capable of being rendered heat recoverable and capable of being cooled from a temperature at which it exists in an austenitic state to a temperature at which it exists in a martensitic state, said alloy being a ternary alloy of copper, aluminium and manganese falling with the area on a ternary diagram defined by the points:
A. 82.9%Cu 12.5%A1 4.6%Mn B. 81.1%Cu 11.0%A1 7.9%Mn C. 80.8%Cu 9.1%A1 10.1%Mn D. 78.6%Cu 8.6%A1 12.8%Mn E. 77.9%Cu 11.0%A1 11.1%Mn F. 79.5%Cu 12.5%A1 8.0%Mn is especially suitable for use in heat recoverable articles which exhibit outstanding stress stability.
An alloy of copper, aluminium and manganese falling within the area on a ternary diagram defined by the points: ABCDEF.
An alloy having a .beta.-brass type construction capable of being rendered heat recoverable and capable of being cooled from a temperature at which it exists in an austenitic state to a temperature at which it exists in a martensitic state, said alloy being a ternary alloy of copper, aluminium and manganese falling with the area on a ternary diagram defined by the points:
A. 82.9%Cu 12.5%A1 4.6%Mn B. 81.1%Cu 11.0%A1 7.9%Mn C. 80.8%Cu 9.1%A1 10.1%Mn D. 78.6%Cu 8.6%A1 12.8%Mn E. 77.9%Cu 11.0%A1 11.1%Mn F. 79.5%Cu 12.5%A1 8.0%Mn is especially suitable for use in heat recoverable articles which exhibit outstanding stress stability.
Description
- 11556~7 .
FIELD OF T~E INVENTION
This invention relates to metal alloys capable of being rendered heat recoverable. In another aspect, ¦ it relates to heat recoverable metal articles.
~ !
BACKGROUND OF THE INVENTION
Materials, both organic and metallic, capable of being rendered heat recoverable are well known, An article made from such materials can be deformed from an original, heat-stable configuration to a second, -heat-unstable configuration. The article is said to be heat recoverable for the reason that, upon the application of heat, it can be caused to revert from its heat-unstable configuration to its original, heat-stable configuration.
Among metals, for example certain alloys of titanium a-ld nickel, the ability to be rendered heat recoverable is a result of the ~act that the metal , undergoes a re~ersible cransformation from an austenitic ` , state to a martensitic state with changes in temperature.
~n article made from such a me'al, for example a hc'low sleeve, is easily deformed from its original configuration to a new configuration when cooled below the temperature at which the metal is transform2d from the austenitic state to the martensitic stàte.
FIELD OF T~E INVENTION
This invention relates to metal alloys capable of being rendered heat recoverable. In another aspect, ¦ it relates to heat recoverable metal articles.
~ !
BACKGROUND OF THE INVENTION
Materials, both organic and metallic, capable of being rendered heat recoverable are well known, An article made from such materials can be deformed from an original, heat-stable configuration to a second, -heat-unstable configuration. The article is said to be heat recoverable for the reason that, upon the application of heat, it can be caused to revert from its heat-unstable configuration to its original, heat-stable configuration.
Among metals, for example certain alloys of titanium a-ld nickel, the ability to be rendered heat recoverable is a result of the ~act that the metal , undergoes a re~ersible cransformation from an austenitic ` , state to a martensitic state with changes in temperature.
~n article made from such a me'al, for example a hc'low sleeve, is easily deformed from its original configuration to a new configuration when cooled below the temperature at which the metal is transform2d from the austenitic state to the martensitic stàte.
2 ~;~
., :
; 1 1 556~7 This temperature, or tem~erature range, is usually referred to as the ~. temperature. When an article thus deformed is warmed to the temperature at which the metal reverts .
back to austenite, referred to as the A temperature or range, the deformed object will revert to its original configuration. Thus, when the hollow sleeve referred to above is cooled to a temperature at which the metal becomes martensitic, it can be easily expanded to a larger diameter, for example, by using a mandrel. If the expanded sleeve is subsequently allowed tG warm to '~he temperature at which the metal reverts back to its austenitic state, the sleeve will revert to its original dimensions.
Ordinarily, such a sleeve -~ould recover all or substantially all of the deformation, i.e. it would revert completely to its original dimensions, However, it should be noted that under certain circumstances the article might be deformed to such an extend that all of the deformation cannot be recovered on heating. Alternatively, if something, e.a an intervening rigid substrate having a greater external dimension than the internal pre- ¦
deformation dimensions of the sleove is interposed w~J-hin the sleeve, the sleeve cannot recover to its original dimensions. Any dimensional change up to the maximum avai~able which an article can recover absent any inter-vening substrate is called the heat recoverable strain.
That portion of the heat recoverable strain which an intervening substrate or other agency precludes recovery of, is referred to as unresolved recovery. Finally, any deformation which exceeds the maximum available heat re-coverable strain is said to effect non-recoverable strain.
., :
; 1 1 556~7 This temperature, or tem~erature range, is usually referred to as the ~. temperature. When an article thus deformed is warmed to the temperature at which the metal reverts .
back to austenite, referred to as the A temperature or range, the deformed object will revert to its original configuration. Thus, when the hollow sleeve referred to above is cooled to a temperature at which the metal becomes martensitic, it can be easily expanded to a larger diameter, for example, by using a mandrel. If the expanded sleeve is subsequently allowed tG warm to '~he temperature at which the metal reverts back to its austenitic state, the sleeve will revert to its original dimensions.
Ordinarily, such a sleeve -~ould recover all or substantially all of the deformation, i.e. it would revert completely to its original dimensions, However, it should be noted that under certain circumstances the article might be deformed to such an extend that all of the deformation cannot be recovered on heating. Alternatively, if something, e.a an intervening rigid substrate having a greater external dimension than the internal pre- ¦
deformation dimensions of the sleove is interposed w~J-hin the sleeve, the sleeve cannot recover to its original dimensions. Any dimensional change up to the maximum avai~able which an article can recover absent any inter-vening substrate is called the heat recoverable strain.
That portion of the heat recoverable strain which an intervening substrate or other agency precludes recovery of, is referred to as unresolved recovery. Finally, any deformation which exceeds the maximum available heat re-coverable strain is said to effect non-recoverable strain.
- 3 -1 ~ 556~7 That the titanium nickel alloys referred to above possess the property of heat recoverability has been known for many years. I~ore recently for example in the United States Patent No. 3,783,037 there is disclosed a method for producing a heat recoverable article in which an alloy comprising an inter-metallic compound that undergoes a diffusionless transformation into a banded martensite upon cooling with or without working is deformed after appropriate heat treatment.
On reheating the article, it at least partly resumes its original shape. The alloys indicated as pre-ferred are copper based alloys which transform into a martensite of pseudo-cubic symmetry including the - binary copper-zinc and copper-aluminium systems and the ternary copper-aluminium-zinc, copper--zinc-tin, copper-zinc-silicon, copper-aluminium-manganese, copper-aluminium-iron and copper-aluminium-nickel systems.
In U,S. Patent ~o. 3,783,037 (Col. 8, Ln. 63 et seq.) it is noted in respect to the copper-aluminium-zinc system that "... as there is pro-gressive increase in the aluminium content and decrease in the zinc content ..., the maximum duc-tility that can be produced in the ternary alloys when deformed at or near the Ms decreases." It is noted that as the aluminium level increases, the maximum obtainable heat recoverable strain decreases.
For example, in alloys of the compositions (by weight) 72D/o copper, 22% zinc and 6% aluminium and 75.5% copper, i - 4 -`'`
.. ~1 1 1~56~7 lP/o zinc and 7.5% aluminium, the maximum heat recoverable strain was reported to be 4.8% and 4.0/0 respectively The clear teaching of this patent is therefore that the aluminium content of the alloy should be reduced as much as possible to achieve maximum heat recoverable strain. Unfortunately, I have found that, unknown to the prior art, reducing the aluminium con-tent has a severe adverse effect on the stability i.e., ability to avoid stress relaxation of the article under conditions of unresolved recovery Additionally, if one follows the teaching of the ~ prior art and avoids ternary alloys containing sig-;~ nificant quantities of aluminium, limitations are encountered in hot working. In particular, low energy input hot working requires avoidance of a second phase in the structure. Unfortunately, low aluminium content alloys must be maintained at very high temperatures, e.g. at least in excess of 650C, to be in the one-phase beta condition the phase desired for hot workability. At such high tempera-tures, tool life is shortened and the avoidance of coarse grain size in the product is difficult.
If a heat recoverable article is recovered onto a substrate such that the substrate prevents full recovery of the article to its original configuration, i.e., under conditions of unresolved recovery, then the residual strain results in a stress in the article.
I have now discovered that all copper alloy composi-tions having the ~-brass structure are more or less _ 5 _ .
' - ' .
1 1556~7 `' ' unstable if complete recovery is prevented. Thus, I
~ find that at moderate temperatures such as would r', typically be seen during service, for example, in hydraulic or electrical applications in aircract, the residual stress in incompletely recovered articles will decay steadily to zero such that after a certain period of time the recovered object, for example, a sleeve recovered about a substrate, can be easily removed from the substrate.
Inasmuch as heat recoverable metals find their greatest utility in applications where they exert a high degree of compressive or other form of stress relaxation process described above is a considerable impediment to the wide spread use of these metals.
For example, parts made from the binary alloys and the specific ternary alloys described in above mentioned U.S. Patent 3,783,037, when prevented from recovering completely to an initial configuration under conditions of about 4.0/O unresolved recovery, ; 20 exhibit complete stress relaxation at 125C, in less than 1,000 hours (equivalent to relaxation within 100 hours at 150C) so that they are essentially useless in many applications.
Therefore, although a wide varity of ~-brass type copper alloy compositions capable of being rendered heat recoverable are known to the prior art, ;those compositions possess serious shortcomings severely limiting their use.
Accordingly, one object of this invention is to provide inproved ~-brass type alloys.
1 ~556~7 ., .
; Another object of this invention is to provide heat recoverable articles of ~-brass type alloys that will exhibit long term stress stability when recovered ; under conditions so that a degree of unresolved ` 5 recovery remains.
Yet another object of this invention is to provide heat recoverable articles of ~-brass type alloys that will preferably maintain a stress for greater than 1,000 hours at 125C or for greater than 100 hours at 150C.
The present invention provides certain ternary alloys of copper, aluminium and manganese which manifest good ductility and are easily worked by hot working techniques in addition to exhibiting excellent long term stress stability. Both good ductility and hot workability are requisite for commercially useful materials. Heat recoverable articles made from the alloys of the present invention exhibit long term stress stability even when recovered under circum-stances such that a level of unresolved recoveryremains.
' The ternary alloys of the present invention fall on or near the line formed by the copper-aluminium, beta ~ (alpha ~ gamma) eutectoid as it crosses the ternary field. This will be referred to hereinafter as the eutectoid line.
The copper-aluminium-manganese ternary alloys of the present invention fall within the area defined in a ternary diagram by the points: ;
,: ~
1 155~8~
A8 2 . 9% Cu 12 . 5% Al 4.6% Mn B. 81 .1% Cu 11 % Al7 . 9% Mn C . 8 0 . 8% Cu 9 ,1% Al 10.1% Mn D. 78 . 6% Cu 8 . 6% Al 12 . 8% Mn E 7 7 . 9% CU 11 % Al 11 .1% Mn F. 79.5% Cu 12 . 5% Al 8 % Mn The present invention will be described in more detail, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a ternary diagram on which is shown the area encompas-sing the copper, aluminium, manganese ternary alloys of the present invention, wherein line XY is the eutectoid line, which for this alloy system is found at a constant aluminium content of about 11. 8%
aluminium.
As previously discussed we have unexpectedly discovered that articles formed from the ~-brass type compositions known to the prior art suffer the serious disadvantage of being unstable with respect to the maintenance of stress when the article has been exposed to modestly elevated temperatures for extended periods of time under conditions of unresolved recovery.
This phenomenon manifests itself in actual use situa-tions when an article made from such an alloy is deformed when in its martensitic state to thereby render it heat recoverable, and then allowed to recover by warming it to a temperature at which the alloy reverts to austenite in a manner that precludes the article from completely recovering to its original 1~556~7 configuration and thereafter exposed to temperatures shown about 80C. That portion of the strain which remains in the article after this partial recovery is, as already indicated, referred to as unresolved recovery.
We have discovered that articles made from ~-brass type compositions known to the prior art are unstable with respect to maintaining adequate stress levels, i.e.,the stress gradually decays to zero, the rate of decay increasing with temperature.
Also, we have discovered that for copper, aluminium and manganese ternary alloys, the tendency towards stress instability is composition dependent and that the most stable alloys are those with a ` 15 composition lying on or near the eutectoid line.
In particular, it is only those alloys falling within the compositional ranges disclosed and claimed herein that do not undergo substantially complete stress relaxation over a period of 1,000 hours or less at 125C (or the equivalent 100 hours at 150C).
The novel ternary alloys which are the subject of the instant invention all have a composition falling on or near the eutectoid line, as defined herein above.
Considering the ternary alloys and referring to Figure 1, there is shown a ternary diagram for alloys of copper, aluminium and manganese on which XY is the eutectoid line for alloys of those elements. For these alloys, there is only one composition on the eutectoid line, the line of maximum stress stability, for any given Ms temperature. The eutectoid line - _ g _ ..
1 155~87 shows a constant aluminium content of about 11 8%.
By adjusting the relative amounts of the individual components, other alloys of the same Ms temperature can be obtained. Usually, however, significant variance from the eutectoid will cause some diminution in desirable properties. For example, in Figure 1 increasing the aluminium content to 12.5%
and adjusting the amounts of copper and manganese to achieve the desired Ms results in moving the alloy to the gamma side of the eutectoid.
By contrast, if the aluminium level is lowered so that the alloy falls on the alpha side of the eutectoid, working is easier. However, the stress stability of the alloy is reduced because of the cumulative effect of 1) moving away from the eutectoid and 2) decreasing the aluminium level. Thus the desirable effect of increasing the alpha content in the alloy to allow easier working for those applica-tions in which articles must be made by cold working must be weighed against the loss of stress stability.
Ternary alloys of copper, aluminium and manganese are not novel in general. However, all the alloys specifically reported by the prior art fall outside the composition range of the instantly claimed alloys and hence suffer from fundamental shortcomings (including stability, as heretofore discussed) which precludes their use under many circumstances. A
consideration of the boundary lines of the claimed - compositional areas indicates why the instantly claimed alloys are uniquely superior. These boundary parameters are, of course, unknown to the prior art.
Additionally, the location of the eutectoid line and its significance to alloy stability are completely unknown to the prior art.
The claim~dcopper, aluminium, manganese ternary alloys are defined by the area encompassed by the lines AB, BC, CD, DE, EF, FA. Compositions to the left of line FA must be heated to temperatures in excess of 650C to preclude formation of the ~ phase of the alloy. As heretofore indicated, presence of the ~-phase results in an alloy of such limited ductility as to effectively preclude its being cold formed into useful articles. Conversely, heating above 650C is undesirable because it fosters excessive grain growth, again affording poor duc-tility. Finally alloys of a composition to the right of line CD must be heated to temperatures in excess of 650C to preclude formation of the a-phase which adversely affects hot working.
The alloys were quenched from 650C into water at 20C. In Figure 1, lines ABC and DEF are the 0C
and -200C Ms lines, respectively. An alloy with an Ms of less than -200C has limited use since it is impractical to store deformed components at lower 25 temperatures. As is known, heat recoverable metallic articles, e.g. couplings, are stored in the deformed conditions, e.g., in liquid nitrogen and recovered on warming or being warmed through their Ms. Conversely, we have found that for these alloy systems an Ms in excess of 0C is incompatible with a stability of at least 1,000 hours at 125C which is equivalent to '~ .
.
~:' ... .
1 155~7 100 hours at 150C. Stability of at least 1,000 hours at 125C is a requirement of electrical connectors under U.S. Government Spec. MIL-C-23353A Paragraph
On reheating the article, it at least partly resumes its original shape. The alloys indicated as pre-ferred are copper based alloys which transform into a martensite of pseudo-cubic symmetry including the - binary copper-zinc and copper-aluminium systems and the ternary copper-aluminium-zinc, copper--zinc-tin, copper-zinc-silicon, copper-aluminium-manganese, copper-aluminium-iron and copper-aluminium-nickel systems.
In U,S. Patent ~o. 3,783,037 (Col. 8, Ln. 63 et seq.) it is noted in respect to the copper-aluminium-zinc system that "... as there is pro-gressive increase in the aluminium content and decrease in the zinc content ..., the maximum duc-tility that can be produced in the ternary alloys when deformed at or near the Ms decreases." It is noted that as the aluminium level increases, the maximum obtainable heat recoverable strain decreases.
For example, in alloys of the compositions (by weight) 72D/o copper, 22% zinc and 6% aluminium and 75.5% copper, i - 4 -`'`
.. ~1 1 1~56~7 lP/o zinc and 7.5% aluminium, the maximum heat recoverable strain was reported to be 4.8% and 4.0/0 respectively The clear teaching of this patent is therefore that the aluminium content of the alloy should be reduced as much as possible to achieve maximum heat recoverable strain. Unfortunately, I have found that, unknown to the prior art, reducing the aluminium con-tent has a severe adverse effect on the stability i.e., ability to avoid stress relaxation of the article under conditions of unresolved recovery Additionally, if one follows the teaching of the ~ prior art and avoids ternary alloys containing sig-;~ nificant quantities of aluminium, limitations are encountered in hot working. In particular, low energy input hot working requires avoidance of a second phase in the structure. Unfortunately, low aluminium content alloys must be maintained at very high temperatures, e.g. at least in excess of 650C, to be in the one-phase beta condition the phase desired for hot workability. At such high tempera-tures, tool life is shortened and the avoidance of coarse grain size in the product is difficult.
If a heat recoverable article is recovered onto a substrate such that the substrate prevents full recovery of the article to its original configuration, i.e., under conditions of unresolved recovery, then the residual strain results in a stress in the article.
I have now discovered that all copper alloy composi-tions having the ~-brass structure are more or less _ 5 _ .
' - ' .
1 1556~7 `' ' unstable if complete recovery is prevented. Thus, I
~ find that at moderate temperatures such as would r', typically be seen during service, for example, in hydraulic or electrical applications in aircract, the residual stress in incompletely recovered articles will decay steadily to zero such that after a certain period of time the recovered object, for example, a sleeve recovered about a substrate, can be easily removed from the substrate.
Inasmuch as heat recoverable metals find their greatest utility in applications where they exert a high degree of compressive or other form of stress relaxation process described above is a considerable impediment to the wide spread use of these metals.
For example, parts made from the binary alloys and the specific ternary alloys described in above mentioned U.S. Patent 3,783,037, when prevented from recovering completely to an initial configuration under conditions of about 4.0/O unresolved recovery, ; 20 exhibit complete stress relaxation at 125C, in less than 1,000 hours (equivalent to relaxation within 100 hours at 150C) so that they are essentially useless in many applications.
Therefore, although a wide varity of ~-brass type copper alloy compositions capable of being rendered heat recoverable are known to the prior art, ;those compositions possess serious shortcomings severely limiting their use.
Accordingly, one object of this invention is to provide inproved ~-brass type alloys.
1 ~556~7 ., .
; Another object of this invention is to provide heat recoverable articles of ~-brass type alloys that will exhibit long term stress stability when recovered ; under conditions so that a degree of unresolved ` 5 recovery remains.
Yet another object of this invention is to provide heat recoverable articles of ~-brass type alloys that will preferably maintain a stress for greater than 1,000 hours at 125C or for greater than 100 hours at 150C.
The present invention provides certain ternary alloys of copper, aluminium and manganese which manifest good ductility and are easily worked by hot working techniques in addition to exhibiting excellent long term stress stability. Both good ductility and hot workability are requisite for commercially useful materials. Heat recoverable articles made from the alloys of the present invention exhibit long term stress stability even when recovered under circum-stances such that a level of unresolved recoveryremains.
' The ternary alloys of the present invention fall on or near the line formed by the copper-aluminium, beta ~ (alpha ~ gamma) eutectoid as it crosses the ternary field. This will be referred to hereinafter as the eutectoid line.
The copper-aluminium-manganese ternary alloys of the present invention fall within the area defined in a ternary diagram by the points: ;
,: ~
1 155~8~
A8 2 . 9% Cu 12 . 5% Al 4.6% Mn B. 81 .1% Cu 11 % Al7 . 9% Mn C . 8 0 . 8% Cu 9 ,1% Al 10.1% Mn D. 78 . 6% Cu 8 . 6% Al 12 . 8% Mn E 7 7 . 9% CU 11 % Al 11 .1% Mn F. 79.5% Cu 12 . 5% Al 8 % Mn The present invention will be described in more detail, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a ternary diagram on which is shown the area encompas-sing the copper, aluminium, manganese ternary alloys of the present invention, wherein line XY is the eutectoid line, which for this alloy system is found at a constant aluminium content of about 11. 8%
aluminium.
As previously discussed we have unexpectedly discovered that articles formed from the ~-brass type compositions known to the prior art suffer the serious disadvantage of being unstable with respect to the maintenance of stress when the article has been exposed to modestly elevated temperatures for extended periods of time under conditions of unresolved recovery.
This phenomenon manifests itself in actual use situa-tions when an article made from such an alloy is deformed when in its martensitic state to thereby render it heat recoverable, and then allowed to recover by warming it to a temperature at which the alloy reverts to austenite in a manner that precludes the article from completely recovering to its original 1~556~7 configuration and thereafter exposed to temperatures shown about 80C. That portion of the strain which remains in the article after this partial recovery is, as already indicated, referred to as unresolved recovery.
We have discovered that articles made from ~-brass type compositions known to the prior art are unstable with respect to maintaining adequate stress levels, i.e.,the stress gradually decays to zero, the rate of decay increasing with temperature.
Also, we have discovered that for copper, aluminium and manganese ternary alloys, the tendency towards stress instability is composition dependent and that the most stable alloys are those with a ` 15 composition lying on or near the eutectoid line.
In particular, it is only those alloys falling within the compositional ranges disclosed and claimed herein that do not undergo substantially complete stress relaxation over a period of 1,000 hours or less at 125C (or the equivalent 100 hours at 150C).
The novel ternary alloys which are the subject of the instant invention all have a composition falling on or near the eutectoid line, as defined herein above.
Considering the ternary alloys and referring to Figure 1, there is shown a ternary diagram for alloys of copper, aluminium and manganese on which XY is the eutectoid line for alloys of those elements. For these alloys, there is only one composition on the eutectoid line, the line of maximum stress stability, for any given Ms temperature. The eutectoid line - _ g _ ..
1 155~87 shows a constant aluminium content of about 11 8%.
By adjusting the relative amounts of the individual components, other alloys of the same Ms temperature can be obtained. Usually, however, significant variance from the eutectoid will cause some diminution in desirable properties. For example, in Figure 1 increasing the aluminium content to 12.5%
and adjusting the amounts of copper and manganese to achieve the desired Ms results in moving the alloy to the gamma side of the eutectoid.
By contrast, if the aluminium level is lowered so that the alloy falls on the alpha side of the eutectoid, working is easier. However, the stress stability of the alloy is reduced because of the cumulative effect of 1) moving away from the eutectoid and 2) decreasing the aluminium level. Thus the desirable effect of increasing the alpha content in the alloy to allow easier working for those applica-tions in which articles must be made by cold working must be weighed against the loss of stress stability.
Ternary alloys of copper, aluminium and manganese are not novel in general. However, all the alloys specifically reported by the prior art fall outside the composition range of the instantly claimed alloys and hence suffer from fundamental shortcomings (including stability, as heretofore discussed) which precludes their use under many circumstances. A
consideration of the boundary lines of the claimed - compositional areas indicates why the instantly claimed alloys are uniquely superior. These boundary parameters are, of course, unknown to the prior art.
Additionally, the location of the eutectoid line and its significance to alloy stability are completely unknown to the prior art.
The claim~dcopper, aluminium, manganese ternary alloys are defined by the area encompassed by the lines AB, BC, CD, DE, EF, FA. Compositions to the left of line FA must be heated to temperatures in excess of 650C to preclude formation of the ~ phase of the alloy. As heretofore indicated, presence of the ~-phase results in an alloy of such limited ductility as to effectively preclude its being cold formed into useful articles. Conversely, heating above 650C is undesirable because it fosters excessive grain growth, again affording poor duc-tility. Finally alloys of a composition to the right of line CD must be heated to temperatures in excess of 650C to preclude formation of the a-phase which adversely affects hot working.
The alloys were quenched from 650C into water at 20C. In Figure 1, lines ABC and DEF are the 0C
and -200C Ms lines, respectively. An alloy with an Ms of less than -200C has limited use since it is impractical to store deformed components at lower 25 temperatures. As is known, heat recoverable metallic articles, e.g. couplings, are stored in the deformed conditions, e.g., in liquid nitrogen and recovered on warming or being warmed through their Ms. Conversely, we have found that for these alloy systems an Ms in excess of 0C is incompatible with a stability of at least 1,000 hours at 125C which is equivalent to '~ .
.
~:' ... .
1 155~7 100 hours at 150C. Stability of at least 1,000 hours at 125C is a requirement of electrical connectors under U.S. Government Spec. MIL-C-23353A Paragraph
4.7.14. It is thus apparent that only those ternary alloys falling within the composition range defined by the perimeter ABCDEF of Figure 1 possess the unique combination of heat recoverability, a useful recovery ; temperature (Ms), worthwhile ductility, and adequate stability.
10As can be seen from Figure 1 we have found that the eutectoid line runs through the claimed areas~
Alloys of a composition falling on or almost on this line are of particularly good stability. As used in the instant specification and the appended claims, the term "eutectoid composition" connotes an alloy whose composition falls either precisely on the eutectoid line or wherein none of the three metal components of the alloy is present in an amount which differs by more than 1.0 wt.% from the percentage of that metal present in the composition corres-ponding preceisely to the eutectoid. It should, of course, be noted that in all instances only ternary ~
compositions falling within the above defined areas ABCDEF are contemplated by the instant invention and that in some instances compositions wherein there is less than 1.0% variation of one or more of the metals from the precise eutectoid composition will fall outside such area. Inasmuch as the boundary lines of the claimed area represent other critical parameters, such compositions, even though eutectoid, have other !~ .
1 155~87 shortcomings and are not within the scope of the present invention.
The following Example illustrates the invention.
The following are examples of alloys according to the present invention having a long term stress stability at 125C for at least 1,000 hours or at least 100 hours at 150C, Each alloy was quenched into water at 20C from 650 C. A 3" long sample was cooled to below the Ms temperature for the alloy and deformed 4.25% by being bent into a U shape about a rod, The sample was heated to either 125C or 150C
while being held in the deformed shape. Periodically the specimen was cooled to room temperature and the constraint was then removed, When this was done, the amount of springback, i.e. movement towards the original configuration, was measured. The specimen was then replaced in the constraint and held for a further period of time at either 125C or 150C.
When upon removal of the constraint no springback was observed, the time that it took to reach that con-dition was taken as the stability limit, '' .
1 1556~7 Copper-Aluminium-Manqanese Ternary Alloys ' Sample Alloy Composition Ms Lifetime at 150 C
Cu Al Mn 1 79 12 7.68 -124C 30,000 hours 2 77.59 11.5 -127C320 hours 3* 79 9 10.2 - 54C90 hours 4 79 9 12 -168C~ 160 hours 83 12 5 + 49 C 20 hours 6 80.510 9.5 _ 43C260 hours * This alloy contained a limited amount of ~-phase.
As is apparent, examples 3 and 5 are directed to compositions outside the scope of this invention.
.... .
All the alloys of the instant invention, possessing as they do outstanding combinations of properties as hereinbefore described, are useful in many and diverse applications. Thus, they may be used to provide hydraulic couplings and electronic connectors as described in United States Patent No. 3,740,839.
The good hot workability of these alloys renders them particularly appropriate for use in extruded products, Thus they may readily be fabricated into wire, rod and various complex profiles. They may be readily stamped, swaged and formed by techniques well known to those skilled in the art.
` ~.T
1 1~56û7 Attention is drawn to United States Patent . 4,146,392 and 4,166,739 which describe ~-brass type ternary alloys of copper, aluminium and zinc, and quaternary alloys of copper, aluminium, zinc and `~ 5 manganese, respectively.
;: - 15 -~, -' , , , ; .
.
:,
10As can be seen from Figure 1 we have found that the eutectoid line runs through the claimed areas~
Alloys of a composition falling on or almost on this line are of particularly good stability. As used in the instant specification and the appended claims, the term "eutectoid composition" connotes an alloy whose composition falls either precisely on the eutectoid line or wherein none of the three metal components of the alloy is present in an amount which differs by more than 1.0 wt.% from the percentage of that metal present in the composition corres-ponding preceisely to the eutectoid. It should, of course, be noted that in all instances only ternary ~
compositions falling within the above defined areas ABCDEF are contemplated by the instant invention and that in some instances compositions wherein there is less than 1.0% variation of one or more of the metals from the precise eutectoid composition will fall outside such area. Inasmuch as the boundary lines of the claimed area represent other critical parameters, such compositions, even though eutectoid, have other !~ .
1 155~87 shortcomings and are not within the scope of the present invention.
The following Example illustrates the invention.
The following are examples of alloys according to the present invention having a long term stress stability at 125C for at least 1,000 hours or at least 100 hours at 150C, Each alloy was quenched into water at 20C from 650 C. A 3" long sample was cooled to below the Ms temperature for the alloy and deformed 4.25% by being bent into a U shape about a rod, The sample was heated to either 125C or 150C
while being held in the deformed shape. Periodically the specimen was cooled to room temperature and the constraint was then removed, When this was done, the amount of springback, i.e. movement towards the original configuration, was measured. The specimen was then replaced in the constraint and held for a further period of time at either 125C or 150C.
When upon removal of the constraint no springback was observed, the time that it took to reach that con-dition was taken as the stability limit, '' .
1 1556~7 Copper-Aluminium-Manqanese Ternary Alloys ' Sample Alloy Composition Ms Lifetime at 150 C
Cu Al Mn 1 79 12 7.68 -124C 30,000 hours 2 77.59 11.5 -127C320 hours 3* 79 9 10.2 - 54C90 hours 4 79 9 12 -168C~ 160 hours 83 12 5 + 49 C 20 hours 6 80.510 9.5 _ 43C260 hours * This alloy contained a limited amount of ~-phase.
As is apparent, examples 3 and 5 are directed to compositions outside the scope of this invention.
.... .
All the alloys of the instant invention, possessing as they do outstanding combinations of properties as hereinbefore described, are useful in many and diverse applications. Thus, they may be used to provide hydraulic couplings and electronic connectors as described in United States Patent No. 3,740,839.
The good hot workability of these alloys renders them particularly appropriate for use in extruded products, Thus they may readily be fabricated into wire, rod and various complex profiles. They may be readily stamped, swaged and formed by techniques well known to those skilled in the art.
` ~.T
1 1~56û7 Attention is drawn to United States Patent . 4,146,392 and 4,166,739 which describe ~-brass type ternary alloys of copper, aluminium and zinc, and quaternary alloys of copper, aluminium, zinc and `~ 5 manganese, respectively.
;: - 15 -~, -' , , , ; .
.
:,
Claims (5)
1. An alloy having a .beta.-brass type structure capable of being rendered heat-recoverable and capable of being cooled from a temperature at which it exists in an austenitic state to a temperature at which it exists in an martensitic state, said alloy being a ternary alloy of copper, aluminium and manganese having an Ms temperature of 0°C or below, exhibiting stress stability of at least 1,000 hours at 125°C in its austenitic state when caused to recover so that a degree of unresolved recovery remains, and having a composition falling within the area on a ternary diagram defined by the points:
A. 82.9% Cu 12.5% A1 4.6% Mn B. 81.1% Cu 11.0% A1 7.9% Mn C. 80.8% Cu 9.1% A1 10.1% Mn D. 78.6% CU 8.6% A1 12.8% Mn E. 77.9% Cu 11.0% A1 11.1% Mn F. 79.5% Cu 12.5% A1 8.0% Mn
A. 82.9% Cu 12.5% A1 4.6% Mn B. 81.1% Cu 11.0% A1 7.9% Mn C. 80.8% Cu 9.1% A1 10.1% Mn D. 78.6% CU 8.6% A1 12.8% Mn E. 77.9% Cu 11.0% A1 11.1% Mn F. 79.5% Cu 12.5% A1 8.0% Mn
2. A ternary alloy of copper aluminium and manganese as claimed in claim 1, which has an eutectoidal composition, said eutectoidal composition being a composition wherein no metal of the group consisting of copper, aluminium and manganese is present in an amount that differs by more than 1% by weight from the amount of said metal in a composition corresponding to an eutectoid composition defined by the line XY of Figure 1.
3. An alloy as claimed in claim 2, which alloy has an eutectoid composition.
4. A heat-recoverable article made from an alloy as claimed in any one of claims 1 to 3.
5. A process for making a heat-recoverable article that exhibits stress stability of at least 1,000 hours at 125°C
when allowed to recover so that a degree of unresolved recovery remains which comprises the steps of:
(a) selecting an alloy as specified in any one of claims 1 to 3;
(b) fabricating said article from the selected alloy into an original, heat-stable configuration (c) cooling said article to a temperature at which the alloy exists in its martensitic state; and (d) deforming said article to a second, heat-unstable configuration from which recovery occurs when said article is warmed to a temperature at which the alloy reverts to austenite from said martensitic state.
when allowed to recover so that a degree of unresolved recovery remains which comprises the steps of:
(a) selecting an alloy as specified in any one of claims 1 to 3;
(b) fabricating said article from the selected alloy into an original, heat-stable configuration (c) cooling said article to a temperature at which the alloy exists in its martensitic state; and (d) deforming said article to a second, heat-unstable configuration from which recovery occurs when said article is warmed to a temperature at which the alloy reverts to austenite from said martensitic state.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379815A CA1155687A (en) | 1976-03-18 | 1981-06-15 | Alloys |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66802876A | 1976-03-18 | 1976-03-18 | |
| US668,028 | 1976-03-18 | ||
| CA274,165A CA1103062A (en) | 1976-03-18 | 1977-03-17 | Alloys |
| CA000379815A CA1155687A (en) | 1976-03-18 | 1981-06-15 | Alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1155687A true CA1155687A (en) | 1983-10-25 |
Family
ID=27164976
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379815A Expired CA1155687A (en) | 1976-03-18 | 1981-06-15 | Alloys |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1155687A (en) |
-
1981
- 1981-06-15 CA CA000379815A patent/CA1155687A/en not_active Expired
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