Annealing of NiTi martensitic memory alloys and product produced thereby
US3953253A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 21, 1973 |
| Grant date | Apr 27, 1976 |
| Priority date | — |
| Expiry date | Dec 21, 1993 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22F1/006
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A process for increasing the tensile strength of a martensitic alloy of titanium and nickel and for improving the alloy's ability to retain its original properties during use by stabilizing it against progressive elongation when cycled through successive martensitic transformations. The process comprises maintaining the alloy under a tensile stress of between about 30,000 and 100,000 psi while annealing the alloy at a temperature above a first diffusional phase transformation temperature. The first diffusional phase temperature is the first temperature above the martensitic transformation range at which there is a negative slope in the electrical resistivity versus temperature curve for the alloy. The product of this process has a tensile strength of at least about 175,000 psi and a martensitic elongation activity under stress of at least about 2% and will survive over one million martensitic transformation cycles when placed under sufficient stress that the elongation activity is about 2%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.