| 摘要 |
PROBLEM TO BE SOLVED: To produce a Nitinol material that is suitable for use in a human body or in other applications.SOLUTION: A fatigue-resistant Nitinol instrument has a working section in a deformed monoclinic martensitic state and an austenite finish temperature in the range of 40 to 60°C. Because the operating environment of the instrument is about 37°C, the working section remains in the monoclinic martensitic state during its use. The relatively high austenite finish temperature and fatigue resistance are achieved by subjecting the nickel-titanium alloy to a final thermal heat treatment in a temperature range of about 410 to 440°C while the nickel-titanium alloy is under constant strain of about 3 to 15 kg. Further, the high austenite finish temperature is achieved without subjecting the alloy to thermal cycling to produce shape memory. Additionally, there are no intermediate processing steps occurring between a step of obtaining a finished diameter of a wire or blank through cold processing and the final thermal heat treatment under constant strain. |
