Nickel-titanium alloy including a rare earth element
View Patent ↗Disclosed herein is a nickel-titanium alloy comprising nickel, titanium, and at least one rare earth element. The nickel-titanium alloy comprises from about 34 at. % to about 60 at. % nickel, from about 34 at. % to about 60 at. % titanium, and from about 0.1 at. % to about 15 at. % at least one rare earth element. The nickel-titanium alloy may further include one or more additional alloying elements. In addition to radiopacity, the nickel-titanium alloy preferably exhibits superelastic or shape memory behavior. Medical devices comprising the nickel-titanium alloy and a method of making them are also disclosed.
1. A nickel-titanium alloy comprising:
nickel at a concentration of from about 34at. % to about 60at. %;
titanium at a concentration of from about 34at. % to about 60at. %; and
at least one rare earth element at a concentration of from about 2.5 at. % to about 15 at. %,
wherein the at least one rare earth element is selected from the group consisting of La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, and U, and
wherein the nickel-titanium alloy comprises an austenite finish temperature at or below 37 ° C., the nickel-titanium alloy being superelastic at body temperature.
2. The nickel-titanium alloy of claim 1 wherein the concentration of the rare earth element is from about 2.5 at. % to about 7.5 at. %.
3. The nickel-titanium alloy of claim 1 , further comprising at least one additional alloying element at a concentration of at least about 0.1 at. % up to about 14.9 at. %.
4. The nickel-titanium alloy of claim 3 , wherein the concentration of the additional alloying element is no more than about 4.9at. % and the additional alloying element is selected from the group consisting of Cr, Co, Fe, and Pd.
5. The nickel-titanium alloy of claim 1 having a radiopacity greater than that of a near-equiatomic binary nickel-titanium alloy.
6. The nickel-titanium alloy of claim 5 , wherein the radiopacity of the nickel-titanium alloy is in the range of from greater than about 1 to about 8 times that of the near-equiatomic binary nickel-titanium alloy when exposed to radiation having an energy in the range of from 15 keV to 150 keV.
7. The nickel-titanium alloy of claim 1 , wherein the nickel-titanium alloy comprises an x-ray contrast in the range of from greater than 1 to about 2 times that of a near-equiatomic binary nickel-titanium alloy when exposed to radiation having an energy in the range of from 40keV to 110keV.
8. The nickel-titanium alloy of claim 1 comprising a recoverable strain of at least about 0.5 % upon removal of a deforming stress at body temperature.
9. The nickel-titanium alloy of claim 1 having a radiopacity greater than that of a near-equiatomic binary nickel-titanium alloy, the concentration of the rare earth element being from about 2.5 at. % to about 7.5 at. %, and further comprising at least one additional alloying element at a concentration of at least about 0.1 at. % to no more than about 4.9 at. %, the additional alloying element being selected from the group consisting of Cr, Co, Fe, and Pd, wherein the nickel-titanium alloy is superelastic and has an austenite finish temperature at or below 37° C.
10. A medical device comprising at least one component comprising a nickel-titanium alloy including nickel at a concentration of from about 34 at. % to about 60 at. %, titanium at a concentration of from about 34 at. % to about 60 at. %, and at least one rare earth element at a concentration of from about 2.5 at. % to about 15 at. %, wherein the at least one rare earth element is selected from the group consisting of La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa and U, and
wherein the nickel-titanium alloy comprises an austenite finish temperature at or below 37° C., the nickel-titanium alloy being superelastic at body temperature.
11. The medical device of claim 10 , wherein the component includes at least one of a wire and a cannula.
12. The medical device of claim 10 , wherein the concentration of the at least one rare earth element is from about 2.5at. % to about 7.5at. % and the nickel-titanium alloy has a radiopacity greater than that of a near-equiatomic binary nickel-titanium alloy.
13. A radiopaque medical device comprising at least one component comprising a nickel-titanium alloy including nickel at a concentration of from about 34at. % to about 60at. %, titanium at a concentration of from about 34at.% to about 60at. %, and at least one rare earth element at a concentration of from about 2.5at. % to about 15at. %, wherein the at least one rare earth element is selected from the group consisting of La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa and U, whereby the nickel-titanium alloy comprises a radiopacity greater than that of a near-equiatomic binary nickel-titanium alloy, and wherein the nickel-titanium alloy further comprises a recoverable strain of at least about 0.5 % upon removal of a deforming stress at body temperature, the nickel-titanium alloy being superelastic at body temperature.
14. The radiopaque medical device of claim 13 , wherein the nickel-titanium alloy has an austenite finish temperature at or below 37° C.
15. The radiopaque medical device of claim 13 , wherein the recoverable strain is in the range of from about 2 % to about 10 %.
16. The nickel-titanium alloy of claim 1 , wherein the concentration of titanium is from about 44 at. % to about 60 at. %.
17. The medical device of claim 10 , wherein the medical device is selected from the group consisting of: a stent, a stent graft, a wire guide, a radiopaque marker or marker band, a catheter, an introducer sheath, an orthodontic arch wire, a vascular plug, an embolic protection filter, and a manipulation, retrieval or occlusive device.
18. The nickel-titanium alloy of claim 10 , wherein the concentration of titanium is from about 44 at. % to about 60 at. %.
19. The radiopaque medical device of claim 15 , wherein the radiopaque medical device is selected from the group consisting of: a stent, a stent graft, a wire guide, a radiopaque marker or marker band, a catheter, an introducer sheath, an orthodontic arch wire, a vascular plug, an embolic protection filter, and a manipulation, retrieval or occlusive device.
20. The nickel-titanium alloy of claim 15 , wherein the concentration of titanium is from about 44 at. % to about 60 at. %.