Fort Wayne Metals Research Products Corporation

W. L. Gore & Associates, Inc.

Fort Wayne Metal Research Products Corporation

Jeremy E Schaffer

Adam J Griebel

Song Cai

Robert A Mitchell

Andrew Kritsch

Ultra-High-Strength (UHS) wires are suited to high strength wire, strands, cables and rope applications including robotics force transmission and other high-performance mono- and multifilament wire applications. The wires exhibit high strength, low stretch and fatigue durability. Exemplary UHS materials include binary molybdenum-rhenium or tungsten-rhenium alloys with between 20 and 50 wt. % rhenium. These alloys are processed from a moderate strength (<2 GPa) warm-drawn rod to drawn monofilament wire with extreme nanocrystalline grain refinement, high apparent fatigue durability, and ultimate strength levels exceeding 5 GPa in all cases, and up to 6.8 GPa at monofilament diameters ranging from 7 to 100 μm.

High strength wire

A magnesium alloy contains a small amount of lithium, zinc, calcium, and manganese. For example, the magnesium alloy may include between 1-5 wt. % lithium, between 0.2-2.0 wt. % zinc, between 0.1-0.5 wt. % calcium, and between 0.1-0.8 wt. % manganese. These alloying elements are all nutrient elements, such that the present alloy can be safely broken down in vivo, then absorbed and/or expelled from the body. Li, Zn, Ca and Mn each contribute to solid-solution strengthening of the alloy. Ca also acts as a grain refiner, while Zn and Ca both form strengthening and corrosion-controlling intermetallic compounds. Optionally, the alloy may also include a small amount of yttrium for added strength and corrosion resistance.

Magnesium-based absorbable alloys

A nickel-titanium alloy is made to be wholly or substantially free of titanium-rich oxide inclusions by including yttrium in an amount up to 0.15 wt. %, with the balance of the alloy being nickel and titanium in approximately equal proportion. For example, a NiTiY alloy may have a composition including, in weight percent based on total alloy weight: between 50 and 60 wt. % nickel; between 40 and 50 wt. % titanium; and between 0.01 and 0.15 wt. % yttrium. The resulting alloy is capable of being drawn into various forms, e.g., fine medical-grade wire, without exhibiting an unacceptable tendency to develop surface defects or to fracture or crack during cold drawing or forging. The resulting final forms exhibit favorable fatigue strength and fatigue-resistant characteristics.

Nickel-titanium-yttrium alloys with reduced oxide inclusions

A group of substantially nickel-free beta-titanium alloys have shape memory and super-elastic properties suitable for, e.g., medical device applications. In particular, the present disclosure provides a titanium-based group of alloys including 16-20 at. % of hafnium, zirconium or a mixture thereof, 8-17 at. % niobium, and 0.25-6 at. % tin. This alloy group exhibits recoverable strains of at least 3.5% after axial, bending or torsional deformation. In some instances, the alloys have a capability to recover of more than 5% deformation strain. Niobium and tin are provided in the alloy to control beta phase stability, which enhances the ability of the materials to exhibit shape memory or super-elastic properties at a desired application temperature (e.g., body temperature). Hafnium and/or zirconium may be interchangeably added to increase the radiopacity of the material, and also contribute to the superelasticity of the material.

Ni-free beta Ti alloys with shape memory and super-elastic properties

Wire products, such as round and flat wire, strands, cables, and tubing, are made from a shape memory material in which inherent defects within the material are isolated from the bulk material phase of the material within one or more stabilized material phases, such that the wire product demonstrates improved fatigue resistance. In one application, a method of mechanical conditioning in accordance with the present disclosure isolates inherent defects in nickel-titanium or NiTi materials in fields of a secondary material phase that are resistant to crack initiation and/or propagation, such as a martensite phase, while the remainder of the surrounding defect-free material remains in a primary or parent material phase, such as an austenite phase, whereby the overall superelastic nature of the material is preserved.

Fatigue strength of shape memory alloy tubing and medical devices made therefrom

Ti&#x2014;Nb&#x2014;Hf/Zr&#x2014;(Cr) alloy shape-memory wires are provided which are suitable for use in medical devices and actuators, and methods for manufacturing such wires are provided. The present shape-memory Ti&#x2014;Nb&#x2014;Hf/Zr&#x2014;(Cr) alloy is a superelastic wire material particularly suited for in vivo applications. For example, the present Ti&#x2014;Nb&#x2014;Hf/Zr&#x2014;(Cr) alloy wire is radiopaque, thereby enabling surgical use of a monolithic, shape-memory alloy wire while preserving the ability to monitor the in vivo location of the wire through X-ray or other radiation-based imaging systems. In addition, the present Ti&#x2014;Nb&#x2014;Hf/Zr&#x2014;(Cr) alloy can be manufactured to exhibit shape-memory alloy material properties without the use of nickel as an alloy constituent, thereby accommodating nickel-sensitive patients. The present Ti&#x2014;Nb&#x2014;Hf/Zr&#x2014;(Cr) alloy can also be processed to exhibit a martensite/austenite transformation temperature near body-temperature, i.e., 37&#xb0; C., so that shape-memory effects can be utilized to accomplish work in vivo.

Titanium-niobium-hafnium alloy shape memory wire

Method for imparting improved fatigue strength to wire made of shape memory alloys, and medical devices made from such wire

A bimetal composite wire including, in cross-section, an outer shell or tube formed of a first biodegradable material and an inner core formed of a second biodegradable material. When formed into a stent, for example, the first and second biodegradable materials may be different, and may have differing biodegradation rates. In a first embodiment, the first biodegradable material of the shell may degrade relatively slowly for retention of the mechanical integrity of a stent during vessel remodeling, and the second biodegradable material of the core may degrade relatively quickly. In a second embodiment, the first biodegradable material of the shell may degrade relatively quickly, leaving a thinner structure of a second biodegradable material of the core that may degrade relatively slowly. The biodegradation rates may be inherently controlled, such as by selection of materials, and also may be mechanically controlled, such as by material thicknesses and the geometric configuration of the shell, core, or overall device. In any embodiment, the metallic scaffold may also be coated with a drug-eluting, biodegradable polymer, to further inhibit neointimal proliferation and/or restenosis.

Biodegradable composite wire for medical devices

Fatigue damage resistant metal or metal alloy wires have a submicron-scale or nanograin microstructure that demonstrates improved fatigue damage resistance properties, and methods for manufacturing such wires. The present method may be used to form a wire having a nanograin microstructure characterized by a mean grain size that is 500 nm or less, in which the wire demonstrates improved fatigue damage resistance. Wire manufactured in accordance with the present process may show improvement in one or more other material properties, such as ultimate strength, unloading plateau strength, permanent set, ductility, and recoverable strain, for example. Wire manufactured in accordance with the present process is suitable for use in a medical device, or other high end application.

Fatigue damage resistant wire and method of production thereof

A wire having an outer shell and a core, the core including at least a first plurality of core segments that may be made of a first core material and a second plurality of core segments that may be made of a second core material different from the first core material. The first and second core segments are arranged in a periodic alternating arrangement along the length of the wire. The outer shell may be made of a metal, such as a biocompatible metal, and the core segments may be made of different materials to provide periodic material properties along the length of the wire. The wire is manufactured by inserting the core segments into the outer shell to form a wire construct, followed by subjecting the wire construct to one or more initial draws while applying a compressive force to the core segments on an upstream side of the die to maintain the core segments in contact with one another upon dense contact between the outer shell and core segments, following by closing of the outer shell onto the core segments, as the wire is pulled through a drawing die. The resulting wire may then be subjected to a plurality of finishing draws. Exemplary applications of the wire include medical devices, such as in vivo heating devices, thermally-actuated snares, in vivo positioning devices, stents, and tissue scaffolds.

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Leo, IN, United States of America

Jeremy E Schaffer