Claims
- 1. A method for expanding the hysteresis loop of a metallic composition in its martensitic state, said hysteresis loop being defined by the M.sub.f, M.sub.s, A.sub.f and A.sub.s temperatures, comprising slowly heating said composition to a temperature above the normal A.sub.s to impart an elevated temperature A.sub.s, hereinafter referred to as A.sub.se, terminating the slow heating and deforming said composition while in the martensitic state to impart heat recoverability.
- 2. The method of claim 1 wherein said slow heating is terminated by cooling to a temperature below said A.sub.se.
- 3. The method of claim 1 wherein said slow heating is terminated by rapid heating.
- 4. The method of claim 1 wherein said composition is deformed before slow heating.
- 5. The method of claim 1 wherein said composition is cooled to a temperature below A.sub.se and is then deformed.
- 6. The method of claim 1 wherein said composition is held at a temperature above the M.sub.s temperature while in the austenitic state for a time sufficient to reduce the loss of reversibility between the martensitic and austenitic states prior to converting the composition to its martensitic state.
- 7. The method of claim 6 wherein prior to said holding step, said composition is heated to a temperature substantially above room temperature and is then quenched.
- 8. The process of claim 7 wherein said quenching temperature is a temperature at which the composition is wholly in the austenitic state.
- 9. A method according to claim 1 wherein said slow heating is at a rate sufficiently slow to substantially prevent martensite reversal to austenite at and above the normal A.sub.s temperature for said alloy.
- 10. The method of claim 3 wherein said rapid heating is at a rate at which the composition reverts from its martensitic state to its austenitic state.
- 11. The method of claim 1 wherein said metallic composition is an alloy comprising copper and a metal selected from the group consisting of zinc and aluminum.
- 12. The method of claim 11 wherein said alloy contains a third metal selected from the group consisting of aluminum, manganese, silicon and tin.
- 13. A method according to claim 1 wherein said deformed composition is heated to a temperature above A.sub.se at a rate at which the composition reverts from its martensitic state to its austenitic state.
- 14. A metal capable of reversible transformations between an austenitic state and a martensitic state with changes in temperature, said metal being the product of the process comprising the steps:
- (a) cooling the metal from a temperature at which it exists in the austenitic state to a temperature at which it exists in the martensitic state;
- (b) heating the metal to a temperature above that at which reversion to the austenitic state normally occurs, said heating being at a rate at which the composition remains substantially in its martensitic state;
- (c) terminating said heating at said temperature; and
- (d) cooling the metal from said temperature to a lower temperature;
- thereby elevating the temperature at which the metal will begin reversion from the martensitic state to the austenitic state to the temperature at which the heating is terminated said metal having been deformed while in the martensitic state from a configuration it possessed in the austenitic state to render the metal heat recoverable.
- 15. A metal according to claim 14 wherein said deforming is accomplished prior to said heating step.
- 16. A metal according to claim 14 wherein said deforming is accomplished after cooling of the metal from the temperature at which heating is terminated.
- 17. A metal according to claim 14 wherein said metal is an alloy comprising copper and an element selected from the group consistig of zinc and aluminum.
- 18. The alloy of claim 17 wherein said element is zinc.
- 19. The alloy of claim 18 wherein said alloy contains a third element selected from the group consisting of aluminum, manganese, silicon and tin.
- 20. The alloy of claim 17 wherein said element is aluminum.
- 21. The alloy of claim 20 wherein said alloy contains a third element selected from the group consisting of manganese, silicon, tin and zinc.
- 22. The alloy of claim 19 comprising 66.2-67.5 wt. % Cu, 29.8-32.0 wt. % Zn, and 1.8-2.7 wt. % Si.
- 23. The alloy of claim 19 comprising by weight 69.7% Cu, 26.3% Zn, and 4% Al.
- 24. The alloy of claim 19 comprising by weignt 66.2% Cu, 37.3% Zn, and 0.5% Al.
- 25. The alloy of claim 19 comprising by weight 64.5% Cu, 34.5% Zn, and 1% Si.
- 26. The alloy of claim 19 comprising by weight 66.5% Cu, 31.75% Zn, and 1.75% Si.
- 27. The alloy of claim 19 comprising by weight 63.7% Cu, 35.3% Zn, and 1% Si.
- 28. The alloy of claim 19 comprising by weight 66.45% Cu, 31.55% Zn, and 2.00% Si.
- 29. The alloy of claim 19 comprising by weight 66.5% Cu, 30.8% Zn, and 19.6% Si.
- 30. The alloy of claim 19 comprising by weight 64.2% Cu, 34.8% Zn, and 1.0% Si.
- 31. The alloy of claim 19 comprising by weight 80.5% Cu, 10.5% Zn, and 9% Al.
- 32. The alloy of claim 21 comprising by weight 80.5% Cu, 10.5% Al, and 9% Mn.
- 33. The alloy of claim 21 comprising by weight 80.8% Cu, 10.5% Al, and 8.7% Mn.
- 34. The alloy of claim 21 comprising by weight 80.49% Cu, 10.5% Al, and 9.01% Mn.
- 35. The alloy of claim 21 comprising by weight 79.2% Cu, 10.0% Al, and 10.8% Mn.
- 36. A metal according to claim 14 having an elongation to failure of at least 5%.
- 37. A metal according to claim 14 wherein said metal is storage stable under atmospheric conditions.
- 38. A metal according to claim 14 wherein the heating rate is less than 1.degree. C/min.
- 39. A metal according to claim 14 wherein said metal has a M.sub.s below room temperature.
- 40. A heat recoverable metallic article comprising a metal capable of reversible transformations between an austenitic state and a martensitic state with changes in temperature, said article being the product of the process comprising the steps:
- (a) fabricating said article in an original configuration;
- (b) cooling the article from a temperature at which the metal exists in the austenitic state to a temperature at which it exists in the martensitic state;
- (c) deforming the article from its original configuration to a second configuration from which recovery is desired;
- (d) heating the article to a temperature above that at which the metal normally undergoes reversion to the austenitic state, said heating being at a rate at which the metal remains substantially in its martensitic state;
- (e) terminating said heating at said temperature; and
- (f) cooling the article from said temperature to a lower temperature,
- 41. An article according to claim 40 wherein the heating rate is less than 1.degree. C/min.
- 42. A heat recoverable metallic article comprising a metal capable of reversible transformations between an austenitic state and a martensitic state with changes in temperature, said article being the production of the process comprising the steps:
- (a) fabricating said article in an original configuration;
- (b) cooling the article from a temperature at which the metal exists in the austenitic state to a temperature at which it exists in the martensitic state;
- (c) heating the article to a temperature above that at which the metal normally undergoes reversion to the austenitic state, said heating being at a rate at which the metal remains substantially in its martensitic state;
- (d) terminating said heating at said temperature;
- (e) cooling the article from said temperature to a lower temperature; and
- (f) deforming the article from its original configuration to a second configuration from which recovery is desired,
- thereby elevating the temperature at which the article will begin recovery towards its original configuration to the temperature at which slow heating is terminated.
- 43. An article according to claim 42 wherein the heating rate is less than 1.degree. C/min.
Priority Claims (1)
Number |
Date |
Country |
Kind |
52343/72 |
Nov 1972 |
UK |
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Parent Case Info
This is a division of application Ser. No. 550,847 filed Feb. 18, 1975 now abandoned.
US Referenced Citations (4)
Non-Patent Literature Citations (2)
Entry |
Titov, P. et al., Hysterisis in Martensitic Transformation on Alloy of Cu-Sn; Akad. Nauk., UKr.SSr; May 1970; pp. 199-204. |
Pops, H.; Martensite in Ternery Cu-Zn Based Beta-Phase Alloys; in Trans. AlME, 239; May 1967; pp. 756-759. |
Divisions (1)
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Number |
Date |
Country |
Parent |
550847 |
Feb 1975 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
417067 |
Nov 1973 |
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