Influence of microstructural purity on the bending fatigue behavior of VAR-melted superelastic Nitinol

Launey, Maximilien E.; Robertson, Scott W.; Vien, Lot; Senthilnathan, K.; Chintapalli, Prashanth; Pelton, Alan R.

doi:10.1016/j.jmbbm.2014.02.008

Cited by 38 publications

(46 citation statements)

References 16 publications

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“…Atom probe tomography (APT) was used to measure phase compositions and precipitate size after aging in a non-transforming Pd 30 Ni 20 Ti 38 Zr 8 Al 4 ''hybrid'' alloy prototype. For the isothermal study, samples were aged at 600°C for 0.25, 1, 3, 5, 10, and 100 h. For the isochronal study, samples were aged for 3 h at 500, 530, and 600°C.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…For automotive applications, use of precious metals such as Pd or Pt may be prohibitive, while the cost-to-benefit ratio may be acceptable in aerospace or medical applications. A cost analysis of stent devices indicated that while replacing a binary NiTi alloy with a low-Ni Pd 30 Ni 20 Ti 46 Al 4 alloy would increase the cost of raw materials by a factor of 3.7; the raw materials make up just a small portion of the device cost to hospitals, resulting in a projected device cost increase of only 8 % [12]. This cost increase might be outweighed by the benefit that a biocompatible PdTi-based device would provide to a severely Ni-hypersensitive patient with no treatment alternative.…”

Section: Design Objectivesmentioning

confidence: 99%

“…Jiang conducted a solution treatment study in which a 950°C 20 h homogenization was followed by 100 h solution treatments at 900, 950, 1000, and 1050°C [20]. [12], Pd (30)(31)(32)(33)(34)(35)(36) Ni (14)(15)(16)(17)(18)(19)(20) Ti (45-46) Al (4)(5) [12] The value of A corresponds to the equilibrium solubility of each component in the phase [20], (e, f) Pd 42.2 Fe 7.8 Ti 44 Al 6 at 600°C [21], and (g, h) Pd 30 Ni 20 Ti 38 Zr 8 Al 4 at 600°C. The x-axis is scaled such that x max = 1/r * , i.e., corresponding to the critical radius for nucleation Solution treatments led to spheroidization and a slight reduction in phase fraction of the Ti-rich secondary phase, but full dissolution of the phase was not observed.…”

Section: Pdti-base Systemsmentioning

confidence: 99%

“…Current consensus in the literature is that in high and ultra-high cycle fatigue, the maximum inclusion size is The dashed arrow indicates the resultant increase in fatigue limit at 10 9 cycles. Results are based on calibrated FIP values computed from FEA simulations on an image-based mesh as reported in [26] a critical factor in determining fatigue behavior [29][30][31]. Launey et al found that in a direct comparison between standard VAR material and high purity (HP) VAR material with reduced maximum inclusion size and area fraction, the HP VAR material exhibited a fatigue limit at 10 7 cycles five times higher than that of the standard VAR material [29].…”

Section: Non-metallic Inclusionsmentioning

confidence: 99%

“…Biocompatibility concerns thus drive the development of low-Ni and Ni-free alternatives to conventional NiTibase SMAs. Preliminary cytology studies by Bender et al indicate that a low-Ni Pd 30 Ni 20 Ti 46 Al 4 alloy shows improved cell viability over binary NiTi when live cell count was measured after exposure to metal alloy powders dispersed in growth media [4]. Additionally, Pd-base alloys have increased radiopacity compared to binary NiTi allowing for better X-ray visibility of devices during placement procedures.…”

Section: Introduction Motivation and Backgroundmentioning

confidence: 99%

See 4 more Smart Citations

Design of Heusler Precipitation Strengthened NiTi- and PdTi-Base SMAs for Cyclic Performance

Frankel

Olson

2015

Shap. Mem. Superelasticity

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For a wide range of actuation applications, the performance of NiTi-based shape memory alloys is limited by cyclic instability associated with accommodation slip. For medical applications, low-Ni compositions are also desirable. Increasing yield strength via precipitation of a coherent nanoscale Ni 2 TiAl-type Heusler phase from a supersaturated B2 matrix is an effective approach for eliminating slip in order to improve the stability of the functional response and increase the structural fatigue life. Quaternary additions that partition into the L2 1 Heusler phase, such as Zr or Pd, are favorable for reducing interphase misfit and maintaining coherency during aging. Phase relations and precipitation kinetics in quaternary Ni(TiZrAl), low-Ni (PdNi)(TiAl), and Ni-free (PdFe)(TiAl) systems are summarized from TEM and atom probe tomography data in the literature. Strengthening behavior during isothermal aging is compared in the NiTiZrAl and PdNiTiAl systems, and recent work characterizing a high-strength, low-Ni ''Hybrid'' (PdNi)(TiZrAl) alloy is presented. A systems design approach is taken in which an optimal microstructure for peak strengthening is identified while other property objectives such as transformation temperature, misfit, radiopacity, and biocompatibility are satisfied.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Design Objectivesmentioning

confidence: 99%

Section: Pdti-base Systemsmentioning

confidence: 99%

Section: Non-metallic Inclusionsmentioning

confidence: 99%

Section: Introduction Motivation and Backgroundmentioning

confidence: 99%

See 3 more Smart Citations

Design of Heusler Precipitation Strengthened NiTi- and PdTi-Base SMAs for Cyclic Performance

Frankel

Olson

2015

Shap. Mem. Superelasticity

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Nickel–Titanium Alloy Laser Micromachining: A Review of Nitinol Laser Processes and Optimization for High‐Speed Laser Cutting

Otto,

Vaseghi,

Davami

2024

Adv Eng Mater

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The nickel‐titanium (NiTi) alloy, “Nitinol”, has become a prominent name in the medical device industry amongst medical device manufacturers. The unique properties of the material, such as the shape memory effect and pseudoelasticity, have earned the material increasing popularity for new product innovations. Amongst the various manufacturing processes for metal alloys, laser micromachining has taken the lead for processing Nitinol‐based products. This literature review provides an analysis of the history and applications of Nitinol, an overview of the microstructure of the material, and a review of the current manufacturing methods for laser cutting medical‐grade Nitinol. A more in‐depth focus is placed on the realm of laser processing and the challenges associated with the manufacturing process. Ultrafast femtosecond pulse processing delivers promising results and quality for manufacturing Nitinol medical devices. However, there exists a need to investigate potential approaches to increase the cutting speed of the process to enhance throughput and stay competitive in a growing market due to the cutting speed being over 4‐times slower than long pulse cutting. Many tactics to address the problem are discussed, ranging from laser selection, processing parameters, and non‐traditional laser processing approaches.This article is protected by copyright. All rights reserved.

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Fluidic and Mechanical Thermal Control Devices

Klinar

Swoboda

Rojo

et al. 2020

Adv Elect Materials

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In recent years, intensive studies on thermal control devices have been conducted for the thermal management of electronics and computers as well as for applications in energy conversion, chemistry, sensors, buildings, and outer space. Conventional cooling or heating techniques realized using traditional thermal resistors and capacitors cannot meet the thermal requirements of advanced systems. Therefore, new thermal control devices are being investigated to satisfy these requirements. These devices include thermal diodes, thermal switches, thermal regulators, and thermal transistors, all of which manage heat in a manner analogous to how electronic devices and circuits control electricity. To design or apply these novel devices as well as thermal control principles, this paper presents a systematic and comprehensive review of the state‐of‐the‐art of fluidic and mechanical thermal control devices that have already been implemented in various applications for different size scales and temperature ranges. Operation principles, working parameters, and limitations are discussed and the most important features for a particular device are identified.

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Influence of microstructural purity on the bending fatigue behavior of VAR-melted superelastic Nitinol

Cited by 38 publications

References 16 publications

Design of Heusler Precipitation Strengthened NiTi- and PdTi-Base SMAs for Cyclic Performance

Design of Heusler Precipitation Strengthened NiTi- and PdTi-Base SMAs for Cyclic Performance

Nickel–Titanium Alloy Laser Micromachining: A Review of Nitinol Laser Processes and Optimization for High‐Speed Laser Cutting

Fluidic and Mechanical Thermal Control Devices

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