A high fatigue resistant nickel-titanium alloy wire, the wire having a transition temperature AF from −15° C. to +10° C. after annealing at a temperature in the range of 700° C. to 900° C., the wire being characterized by a Full-Width at Half-Maximum (FWHM) of austenite nickel-titanium diffraction peak in the range of 0.6° 2Φ to 0.7° 2Φ in a X-ray diffraction pattern using a Cu Ka radiation source.
