Manufacture of fine-grained material for use in medical devices
Medical devices are manufactured from fine grained materials, processed from of a variety of metals and alloys, such as stainless steel, cobalt-chromium and nickel-titanium alloys. A fine grained metal or alloy is formed from a specimen rapidly heated to its recrystallization temperature, and then subjected to high temperature, multi-axial deformation, for example, by heavy cross-forging or swaging. The deformed specimen may be cooled and reheated to a second recrystallization temperature. The metal or alloy in the specimen is then allowed to recrystallize, such that the grain size is controlled by quenching the specimen to room temperature. A desired medical device is then configured from the fine grained material. Decreasing the average grain size of a substrate material and increasing the number of grains across a thickness of a strut or similar component of the medical device increases the strength of the device and imparts other beneficial properties into the device.
1. A medical device for use in treating a human patient, comprising:
a metal alloy substrate having an average grain size in the range of one to ten microns.
2. The device of claim 1 , wherein the substrate is a titanium based alloy.
3. The device of claim 1 , wherein the medical device is a stent.
4. The device of claim 3 , wherein the stent is configured with a plurality of struts having a thickness, such that the number of grains across a strut thickness is in the range of five to fifteen.
5. The device of claim 3 , wherein the stent is configured with a plurality of elongate elements having a thickness, such that the average number of grains across an element thickness is more than six.
6. An intravascular stent for use in a body lumen, comprising:
a plurality of cylindrical rings interconnected to form the stent, each cylindrical ring having a first delivery diameter and a second expanded diameter; and
each cylindrical ring being formed from a fine grained material having an average grain size of one to ten microns.
7. The intravascular stent of claim 6 , further comprising at least one straight link attaching each cylindrical ring to an adjacent cylindrical ring.
8. The intravascular stent of claim 6 , further comprising at least one undulating link attaching each cylindrical ring to an adjacent cylindrical ring.
9. The intravascular stent of claim 6 , further comprising at least one undulating link attaching a first cylindrical ring to a first adjacent cylindrical ring, and at least one straight link attaching a second cylindrical ring to a second adjacent cylindrical ring.
10. The intravascular stent of claim 6 , wherein each cylindrical ring includes a proximal end, a distal end and a cylindrical wall extending circumferentially between the proximal end and the distal end, and further including an undulating link positioned substantially within the cylindrical wall of a first cylindrical ring so as to attach the first cylindrical ring to an adjacent cylindrical ring.
11. A stent comprising a substrate having an average grain size in the range of one to ten microns.
12. The stent of claim 11 , wherein the stent is configured with a plurality of struts having a thickness, such that the number of grains across a strut thickness is in the range of five to fifteen.
13. The stent of claim 11 , wherein the stent is configured with a plurality of elongate elements having a thickness, such that the average number of grains across an element thickness is more than six.
14. The stent of claim 11 , wherein the substrate is a metal selected from the group consisting of titanium and tantalum.
15. The stent of claim 11 , wherein the substrate is a metal alloy selected from the group consisting of stainless steel alloys, cobalt-chromium alloys, nickel-titanium alloys, platinum-iridium alloys, titanium based alloys and tantalum based alloys.