Fort Wayne Metals - Technical Blog

How advanced processing is revolutionizing tungsten performance

Thu, 10 Jul 2025 15:08:36 Z

Tungsten is a material known for its exceptional hardness, high melting point, and resistance to wear. These properties make it indispensable in industries like aerospace, robotics, and industrial manufacturing. However, the performance of tungsten depends heavily on how it is processed.

Traditional tungsten processing methods, such as warm working and hot-to-warm drawing, have been effective, but come with limitations. These conventional techniques often result in lower tensile strength, increased brittleness, and an inconsistent microstructure. As industries demand higher performance materials, advanced processing techniques have emerged to significantly enhance tungsten’s mechanical properties.

Advancements in high-strength tungsten processing

Fort Wayne Metals has developed an innovative processing technique that significantly enhances tungsten’s performance. Through a series of mechanical treatments, this method increases the ultimate tensile strength by over 30% while also improving ductility and structural consistency.

Key advantages of this high-strength processed tungsten include:

Enhanced tensile strength – The material can withstand significantly greater mechanical stress, reaching tensile strengths exceeding 6 GPa.
Improved ductility – Even at small diameters, this tungsten remains more ductile, reducing the risk of brittle fractures.
Uniform grain structure – The refined microstructure ensures consistent properties across long material lengths, enhancing reliability in demanding applications.

Comparing high-strength and conventionally processed tungsten

Figures from recent testing illustrate the stark differences between conventional and high-strength processed tungsten. When comparing 25 µm (0.001 in) wire, Fort Wayne Metals’ advanced tungsten exhibited strength improvements from approximately 4 GPa to 5.5 GPa. Additionally, the work energy to fracture—an indicator of material toughness—more than tripled from 40 to 125 mJ/mm³.

Further process refinements and diameter reduction to 12 µm (~0.0005 in) have yielded even more impressive results, with strength reaching nearly 6.8 GPa (1 million psi). These properties suggest significant benefits for applications where structural fatigue performance is critical, such as robotic manipulation.

The future of tungsten in high-performance applications

With its superior mechanical properties, high-strength processed tungsten is set to play a crucial role in next-generation technologies. Fort Wayne Metals continues to push the boundaries of tungsten processing, with ongoing research into structural fatigue durability and total applied performance. As industries evolve, materials like high-strength tungsten will be essential in meeting the increasing demands for reliability and efficiency.

Optimizing medical devices: The effect of platinum on Nitinol DFT® composite wire

Fri, 16 May 2025 10:45:40 Z

The medical device industry is constantly innovating to create smaller, more effective tools that improve patient outcomes. Among these advancements is the development of Nitinol DFT® wire with a platinum core, a material combining the superelastic properties of Nitinol with the radiopacity of platinum. This breakthrough, now two decades running, enables enhanced imaging visibility and mechanical performance, addressing critical challenges in designing minimally invasive medical devices.

Enhancing performance: The role of platinum in Nitinol alloys

Superelastic Nitinol is a preferred material in medical applications due to its shape memory and flexibility. However, the fine diameter of many medical wires reduces visibility under X-ray imaging, a limitation that can hinder precision during procedures. To address this, Fort Wayne Metals developed Nitinol DFT® composite wire, integrating a superelastic Nitinol sheath with a platinum core, and has continued to refine process and material performance since its early 2000s inception. This combination leverages Nitinol’s mechanical advantages and platinum’s radiopacity, creating a wire with properties tailored to medical device specifications.

Key findings: How platinum content affects performance

This study investigated how varying platinum core percentages (10%, 20%, 30%, and 40%) impact the performance of Nitinol DFT® composite wire. The team conducted several tests to evaluate mechanical properties, superelastic behavior, and fatigue performance.

Bend and free recovery: Increasing the platinum content reduced the wire's ability to recover its original shape after deformation. Wires with higher platinum percentages required more energy (heat) to return to their initial form, showing a more sluggish recovery. For example, the "Active Af" (transformation temperature) increased by approximately 6°C for wires with a 40% platinum core compared to solid Nitinol.
Tensile properties: Higher platinum content also decreased tensile and plateau stresses, while increasing residual elongation. This indicates that devices made from wires with larger platinum cores may exhibit reduced expansion forces and less shape recovery after deformation.
Fatigue performance: Despite these changes, platinum content did not significantly affect rotating bending fatigue performance. Both solid Nitinol and composite wires with various platinum percentages achieved over 10 million cycles at low strain levels (0.9%), demonstrating the material’s durability under cyclic loading.

Implications for medical device design

The findings highlight the need to carefully balance radiopacity and mechanical performance when incorporating platinum into Nitinol wires. While a higher platinum core improves visibility under imaging, it also compromises some of Nitinol’s hallmark superelastic properties. Designers must weigh these trade-offs depending on the device’s intended application.

For example, cardiovascular stents requiring precise placement under X-ray may benefit from a higher platinum content, prioritizing radiopacity. On the other hand, devices needing exceptional shape recovery, such as certain orthopedic implants, may favor lower platinum percentages to retain Nitinol’s full superelastic potential.

Conclusion

Nitinol DFT® with a platinum core represents a significant step forward in advancing medical device technology. By integrating two complementary materials, it provides a versatile solution for applications requiring both visibility and mechanical precision. As research continues, further refinements in wire composition and processing could unlock even greater performance, paving the way for next-generation medical devices.

The assessment of magnesium wire coatings: Paving the path for absorbable implants

Mon, 05 Feb 2024 15:16:00 Z

Advancing biodegradable medical devices with coated magnesium wire

In recent years, the medical field has witnessed significant innovation in developing absorbable materials for permanent implants. These advances promise to revolutionize devices like stents, staples, and sutures by eliminating the need for permanent materials that may cause long-term complications or additional surgeries to remove them. Among these developments, magnesium (Mg) alloys have emerged as a frontrunner due to their biocompatibility and ability to degrade harmlessly within the body.

Challenges of magnesium in medical applications

Despite its appeal, magnesium's relatively rapid degradation rate poses challenges, particularly for fine diameter wires required in certain medical applications. These wires must maintain their mechanical integrity throughout the healing process to provide sufficient support. This dilemma has driven researchers from our Research and Development team to explore coating techniques that slow the degradation rate while preserving the absorbable magnesium wire’s flexibility and strength.

Innovative coatings for magnesium wire

For this study, Fort Wayne Metals’ patented magnesium alloy LZ21 wire, designed for ductility and moderate strength, was processed into wires with a final diameter of 0.3 mm and subjected to three conditions: bare, anodized, and polymer-coated. The polymer layer, made from polycaprolactone (PCL), was applied over the anodized wire to create a dual-layer system.

Key findings from in vitro and in vivo testing

In vitro testing revealed substantial differences in degradation rates between the coated and bare wires. Bare wires lost 82% of their mechanical strength within seven days. In contrast, anodized wires retained 60% of their strength, and PCL-coated wires maintained over 90% of their strength even after 14 days. These results highlight the significant protective benefits of both anodization and polymer coatings.

In vivo testing, conducted via subcutaneous implantation in mice, showed slower degradation rates compared to in vitro conditions. Bare wires retained 84% of their structure after seven days and 60% after 33 days. The PCL-coated wires exhibited almost no signs of degradation at either time point, underscoring their effectiveness as a corrosion barrier.

Implications for medical device development

These findings offer promising implications for the future of absorbable medical devices. The dual-layer coating system delays corrosion, preserving the mechanical properties through the critical tissue healing period. The study also established an in vitro-in vivo correlation (IVIVC) factor of 8.1, which provides a foundation for predicting real-world performance based on accelerated laboratory testing.

Future directions

While these coatings are promising, further research is needed to fine-tune their performance. For instance, modifying the thickness or composition of the polymer layer could optimize the balance between protection and timely degradation. Additionally, studying the effects of plastic deformation during implantation on corrosion rates is needed to ensure real-world applicability.

Conclusion

The use of coated magnesium wire marks a significant step forward in creating safer, more effective absorbable medical devices. By addressing magnesium's rapid degradation, these innovative coatings pave the way for a new generation of implants that support healing while seamlessly integrating into the body's natural processes.

Magnetic susceptibility of medical metals: New insights for MR conditional devices

Tue, 16 May 2023 15:13:00 Z

A recent study, coauthored by Fort Wayne Metals and MED Institute researchers, provides valuable insights into the magnetic susceptibility of 45 metallic materials commonly used in medical devices. This research offers critical data for selecting materials in applications where MR safety is a concern.

Why magnetic susceptibility matters in medical devices

Magnetic susceptibility refers to a material’s degree of magnetization in response to an external magnetic field. In the medical field, this property is essential for devices that may be used in magnetic resonance (MR) environments. Materials with high magnetic susceptibility can:

Cause image distortion in MRI scans
Generate dangerous forces and torques within strong magnetic fields
Impact the safety of implanted or external medical devices

To achieve an MR Conditional label, a device must be designed with materials that minimize these effects.

Key findings

The study measured the magnetic susceptibility of a wide range of metals and alloys, presenting results in ascending order. Key takeaways include:

Titanium and Nitinol alloys: Extremely low magnetic susceptibility, making them ideal for MR-compatible implants
Cobalt-chromium (CoCr) alloys: Moderate susceptibility but often acceptable for certain applications
Stainless steel: Vary widely depending on composition and cold working, with some grades exhibiting significantly higher susceptibility
Nickel-based alloys: Generally higher susceptibility, which can limit MR compatibility

Material selection for MR Conditional devices

For medical device manufacturers, this data supports informed material selection

Best choices for MR compatibility: Titanium and Nitinol alloys
Moderate risk materials: Certain CoCr alloys and austenitic stainless steels
High susceptibility materials to avoid: Cold-worked stainless steels and some nickel-based alloys

Conclusion

This study provides a comprehensive reference for selecting medical metals based on magnetic susceptibility. By considering this factor early in the design process, manufacturers can enhance MR safety, improve imaging quality, and ensure compliance with MR Conditional labeling standards.

Advancing neurovascular treatment: FeMnN—Mo composite wires for absorbable flow Diverters

Mon, 06 Feb 2023 14:35:00 Z

The growing demand for innovative solutions to treat intracranial aneurysms has driven advancements in medical materials. Researchers at Fort Wayne Metals have developed FeMnN-Mo composite wires as a foundation for absorbable flow diverters. These devices, designed to treat aneurysms by redirecting blood flow and promoting clot formation, are expected to dissolve after achieving their purpose, reducing long-term complications.

Challenges with existing materialsExisting flow diverters employ permanent metals such as 35N LT® or Nitinol. These devices function well but are unnecessary after aneurysm occlusion and can impede secondary procedures. Absorbable polymers like polyglycolic acid (PGA) and poly-l-lactic acid (PLLA) have been investigated as temporary options but require larger struts for sufficient strength, compromising device profile and flexibility. Absorbable Mg- and Fe-based devices have also been investigated but suffer from rapid degradation and premature fracture.

Innovative FeMnN-Mo composite wiresThe study introduces composite DFT® wires made of:

FeMnN shell: Provides strength, elasticity, and a cell-friendly surface.
Molybdenum (Mo) core: Offers enhanced radiopacity and staged corrosion protection.

These wires, available in diameters as fine as 25 µm, mimic the dimensions of traditional metallic flow diverters while addressing their limitations.

Key findings

Mechanical performance

The composite wires achieved mechanical properties comparable to non-absorbable counterparts, with customizable strength and elasticity by varying Mo content.
Braided prototypes demonstrated crush resistance similar to commercial devices, making them suitable for neurovascular applications.

Enhanced radiopacity

The Mo core significantly improved visibility under fluoroscopic guidance, essential for precise device placement.
Radiopacity increased proportionally with Mo content, ensuring adequate imaging performance without permanent markers.

Corrosion Behavior

In vitro and in vivo tests showed progressive and controlled degradation of the FeMnN shell, while the Mo core remained intact for at least six months.
This staged degradation minimizes the risk of premature fragmentation.

Biocompatibility

Cytotoxicity testing confirmed minimal impact on cellular health, supporting the material's safety for clinical use.

Advantages for Neurovascular Devices

Minimized profile: Comparable to traditional flow diverters, enabling easier navigation in small vessels.
Reduced long-term risks: Absorbability eliminates concerns like chronic inflammation, side branch blockage, and imaging artifacts from permanent implants.
Improved healing: Supports endothelial tissue regeneration over aneurysm necks for effective occlusion.

Future Directions
While these findings highlight the potential of FeMnN-Mo DFT® composite wires, further research is needed to optimize their degradation timeline and assess long-term clinical performance. Exploring additional configurations and alloy combinations could further enhance their functionality.

Conclusion
FeMnN-Mo DFT® composite wires represent a promising step forward in the development of absorbable flow diverters. By addressing critical challenges in material performance and compatibility, this innovation paves the way for safer and more effective neurovascular treatments.

Superelastic conductor materials: Enhancing implantable lead durability

Mon, 22 Aug 2022 12:00:00 Z

Implantable biostimulation leads are essential components in cardiostimulation and neurostimulation devices. These highly engineered wire constructs must endure millions of flexural cycles over decades of use. Fort Wayne Metals has introduced a new wire construct concept that significantly improves fatigue resistance, potentially enhancing the longevity and reliability of implantable medical devices.

Breakthrough in conductor materials

Traditional biostimulation leads have relied on materials like 35N LT® (CoNiCrMo), which offer good fatigue resistance but still present limitations in extreme flexural conditions. The introduction of Nitinol-based conductors presents a major advancement. When substituted for 35N LT®, Nitinol demonstrates a 50% to 100% improvement in cyclic strain-loading fatigue performance, making it a promising alternative for long-term implantable applications.

The new composite wire, NiTi-DFT®-30Ag, features a high-conductivity pure silver core encased in a Nitinol outer sheath. While its ultimate strength of 1000 MPa is lower than the 1600 MPa of traditional 35N LT®-DFT®-28Ag, it requires significantly more energy to fracture—65.9 mJ/mm³ compared to 23.7 mJ/mm³. This enhanced toughness suggests improved resilience under continuous flexing conditions.

Advantages for medical device applications

Nitinol’s unique superelastic properties allow it to elastically recover from strains exceeding 10%, making it an excellent candidate for applications requiring high fatigue resistance. This property has already led to its widespread use in guidewires and stents, and its introduction into implantable leads could revolutionize the field.

A key challenge in integrating Nitinol into lead designs has been its elasticity, which complicates coil formation and shape retention. However, Fort Wayne Metals has successfully demonstrated that polyimide coatings can provide the necessary electrical insulation while withstanding high-temperature shape-setting processes. This breakthrough enables the use of Nitinol-based bifilar coils, which maintain electrical isolation even after exposure to 450-550°C secondary shape-setting.

Potential future applications

The ability to shape set Nitinol-based conductors at high temperatures opens up new design possibilities for implantable leads. For example, future pacing and defibrillation systems may incorporate hybrid designs with transmyocardial leads that require exceptional flexibility and durability. Additionally, Nitinol-based leads could be programmed with deployable shapes that enhance passive fixation, reducing the risk of dislodgement or migration.

Beyond cardiac applications, neurostimulation devices could benefit from Nitinol’s compliance and resistance to mechanical fatigue. As neurostimulation leads are often subjected to constant movement within the body, improved fatigue resistance could lead to longer-lasting and more reliable therapies for conditions such as Parkinson’s disease and chronic pain.

Conclusion

The introduction of Nitinol-based conductors represents a significant advancement in implantable lead technology. With superior fatigue resistance, enhanced durability, and the ability to maintain electrical integrity under extreme conditions, these materials have the potential to redefine the future of biostimulation devices. As research and development continue, Nitinol-based leads may soon become the new standard for next-generation implantable medical devices.

Super-elastic alloys with gigapascal plateau strengths: Advancing medical and space applications

Thu, 04 Mar 2021 12:00:00 Z

Nitinol alloys have long been a core material in medical and industrial applications due to their unique super-elastic properties. Fort Wayne Metals developed a new generation of Nitinol-based super-elastic (SE) alloys that push the previous boundaries of strength and performance. With upper plateau strengths exceeding 1.0 GPa and lower plateau strengths above 600 MPa, these advanced materials unlock new possibilities across a range of demanding applications.

Enhanced strength for medical applications

The ability to achieve high plateau stresses allows medical device engineers to develop components with thinner profiles while maintaining or even increasing mechanical performance. For instance, vascular guidewires and orthodontic arch wires made from these advanced Nitinol alloys can deliver greater force in smaller wire diameters.

Tensile stress-strain testing of one such alloy, NiTiNbY, revealed remarkable improvements over traditional binary Nitinol alloys. NiTiNbY demonstrated a forward loading plateau stress of 1100 MPa—an increase of more than 65% compared to conventional Nitinol’s 650 MPa. Additionally, its unloading plateau stress is double that of standard Nitinol, while its axial elastic modulus is 40-50% higher. These improvements mean that medical devices, such as stents and guidewires, can be designed with thinner structures without compromising outward force or performance.

While higher stresses can enhance push-ability and torque in guidewires, engineers must consider durability, particularly for permanent implants. However, for temporary devices, the benefits are substantial. Orthodontic arch wires, for example, can provide double the bending force compared to traditional Nitinol wires, enhancing treatment efficiency.

Superelasticity at cryogenic temperatures for space applications

One of the most remarkable attributes of these alloys is their ability to retain super-elastic properties even at extremely low temperatures. Traditional Nitinol alloys transform to martensite upon cooling, losing their super-elastic behavior. However, NiTiNbY and similar compositions maintain stable super-elastic recovery even at -130°C, as shown in stress-strain testing. This property makes them ideal for applications in space exploration and other extreme environments.

Potential space applications include deployable structures, springs, and even advanced tire designs for extraterrestrial exploration. A spring or textile-based tire made from NiTiNbY alloy could be compacted for transport and then deployed to operate over a broad temperature range while maintaining high load-carrying capabilities.

If you are interested in the future of Nitinol alloy spring tires and our collaboration with NASA, please explore our most recent research.

The challenge of finding a Nitinol alternative

Mon, 23 Nov 2020 15:09:00 Z

Nitinol has long been the material of choice for medical devices that require super-elasticity. Its ability to recover from deformation without permanent damage makes it essential in applications like stents, guidewires, and orthopedic implants. However, concerns over Nitinol’s nickel content with potential allergic reactions from patients have driven research into alternative materials with comparable properties.

The rise of Ni-free β-Ti alloys

One promising alternative is a Ni-free β-Ti alloy composed of Ti-40Hf-13Nb-4.5Sn (wt.%). This alloy demonstrates large and stable super-elastic behavior at room temperature, a key requirement for medical applications. Unlike other β-Ti alloys that struggle to achieve the recoverable strain of Nitinol, this material exhibits up to 5.3% total recoverable strain at 6% deformation—putting it much closer to Nitinol’s performance.

Key advantages of Ti-Hf-Nb-Sn (THNS) alloy

This Ni-free β-Ti alloy offers several advantages beyond eliminating nickel:

Comparable mechanical properties: Its mechanical strength and fatigue performance are in the same range as superelastic Nitinol.
Customizable plateau strengths: Similar to Ni-rich Nitinol, the alloy's performance can be adjusted through low-temperature aging.
Manufacturability at scale: The alloy has been successfully produced in 100 kg quantities using commercial production lines, making it feasible for industrial-scale applications.
High X-ray visibility: The presence of hafnium enhances radiopacity, which is beneficial for medical imaging during procedures.
Biocompatibility and corrosion resistance: These characteristics make it a strong candidate for implants, especially for nickel-sensitive patients.

Overcoming manufacturing challenges

Many β-Ti alloys have struggled with manufacturability due to high heat treatment requirements and oxidation concerns. However, this alloy achieves optimal mechanical properties at lower temperatures (~600°C), reducing the risk of oxidation and making shape-setting more practical. Unlike other high-zirconium β-Ti alloys, which pose ignition risks during processing, this alloy has demonstrated safer large-scale production capabilities.

A substitute for Nitinol?

Despite years of research, no Ni-free β-Ti alloy has been successfully substituted for Nitinol in the medical device industry—until now. With its stable super-elasticity, comparable mechanical properties, and improved manufacturability, this Ti-Hf-Nb-Sn alloy presents a viable alternative for applications such as orthopedic implants, dental devices, and neurovascular components.

As the medical industry continues to prioritize patient safety and material innovation, this breakthrough may pave the way for the next generation of superelastic biomaterials.

CoNiCr-Nitinol composite wires for guidewire applications

Mon, 17 Feb 2020 12:00:00 Z

Fort Wayne Metals developed a CoNiCr-Nitinol composite wire targeted for use in advanced guidewire applications. This novel material combines the strength and stiffness of CoNiCr alloys with the superelasticity of Nitinol, offering a seamless transition from proximal stiffness to distal flexibility. These properties may enhance physician control, improve tip performance, and facilitate the crossing of chronic total occlusions (CTOs) without requiring a jointed core wire.

Material composition and manufacturingThe composite wire consists of:

Outer Shell: 35N LT® (CoNiCrMo alloy) for high strength and stiffness
Core: Ni50.8Ti49.2 Nitinol for superelasticity and kink resistance

Manufactured using DFT® technology, the wire undergoes co-processing, cold reduction, and heat treatments. This process combines two dissimilar materials into a single wire system, achieving optimal strength, flexibility, and superelastic performance.

Key performance characteristics

Mechanical strength and flexibility

The CoNiCr shell provides an initial elastic modulus of 197 GPa and an ultimate tensile strength of 2600 MPa.
The Nitinol core maintains an elastic modulus of 48 GPa with an ultimate tensile strength of 1170 MPa.
The wire demonstrates a seamless transition from stiffness to flexibility, allowing for precise control.

Torque control and one-to-one response

Rotational testing confirmed minimal lag between proximal and distal ends, providing sufficient torque transmission.
Optical tracking in a whip test showed that the wire exceeded ASTM F2819 standards for straightness.

Bending and kink resistance

The composite wire maintains higher bending stiffness in the proximal section for pushability.
The Nitinol core offers lower bending resistance in the distal end, improving navigation and kink resistance.

Joint-free design

Unlike traditional guidewires that require soldering or adhesives to join different materials, this composite wire integrates high strength and superelasticity into a single, continuous structure.
This composite wire product has the potential to reduce failure points and enhance reliability.