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Abstract

An improved guiding member for advancing a catheter within a body lumen having a unique combination of superelastic characteristics. The superelastic alloy material has a composition consisting of titanium and nickel and may have one or more elements selected from the group consisting of iron, cobalt, vanadium and copper. The alloy material is cold worked and then heat treated at a temperature well above the austenite-to-martensite transformation temperature, while being subjected to longitudinal stresses equal to about 5 to about 50% of the room temperature yield stress to impart to the metal a straight 'memory'. The guiding member using such improved material exhibits a stress-induced austenite-to-martensite phase transformation at an exceptionally high constant yield strength of at least 90 ksi for solid members and at least 70 ksi for tubular members with a broad recoverable strain of at least about 4% during the phase transformation.

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First Claim