Grain Nucleation and Growth in Deformed NiTi Shape Memory Alloys: An In Situ TEM Study

Burow, Juri; Frenzel, Jan; Somsen, Christoph; Prokofiev, Egor; Valiev, Ruslan Z.; Eggeler, Gunther

doi:10.1007/s40830-017-0119-y

Cited by 11 publications

(4 citation statements)

References 67 publications

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“…Increasing the fatigue strength [180,[184][185][186][192][193][194][195] is also ensured by electropolishing (EP) and magneto-electropolishing (MEP) in a constant magnetic field [49][50][51][192][193][194][195]230,231]. Additive technologies [232], drawing [233] or cold rolling [234], high-pressure torsion (HPT) [235], and equal channel angular pressing (ECAP) [236] can also be used for the manufacturing of tools using nitinol alloy. The favourable fineness of the austenitic matrix grain [237,238] depends on the heat treatment conditions [239,240] and the given technological processes, deciding the course of the Ni 4 Ti 3 [241,242] dispersion precipitation processes in austenite and martensitic transformation, respectively, in the B19 or R structure phases [242,243].…”

Section: Methods and Tools Of Root Canal Preparation In Endodontic Treatmentmentioning

confidence: 99%

Is Gutta-Percha Still the “Gold Standard” among Filling Materials in Endodontic Treatment?

Dobrzańska¹,

Dobrzański²,

Dobrzański³

et al. 2021

Processes

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The paper is an extensive monographic review of the literature, and also uses the results of the authors’ own experimental research illustrating the noticed developmental tendencies of the filling material based on gutta-percha. The whole body of literature proves the correctness of the research thesis that this material is the best currently that can be used in endodontics. Caries is one of the most common global infectious diseases. Since the dawn of humankind, the consequence of the disease has been the loss of dentition over time through dental extractions. Both tooth caries and tooth loss cause numerous complications and systemic diseases, which have a serious impact on insurance systems and on the well-being, quality, and length of human life. Endodontic treatment, which has been developing since 1836, is an alternative to tooth extraction. Based on an extensive literature review, the methodology of qualifying patients for endodontic treatment was analyzed. The importance of selecting filling material and techniques for the development and obturation of the root canal during endodontic treatment was described. Particular attention was paid to the materials science aspects and the sequence of phase transformations and precipitation processes, as well as the need to ensure the stoichiometric chemical composition of Ni–Ti alloys, and the vacuum metallurgical processes and material processing technologies for the effects of shape memory and superelasticity, which determine the suitability of tools made of this alloy for endodontic purposes. The phenomena accompanying the sterilization of such tools, limiting the relatively small number of times of their use, play an important role. The methods of root canal preparation and obturation methods through cold side condensation and thermoplastic methods, including the most modern of them, the thermo-hydraulic condensation (THC) technique, were analyzed. An important element of the research hypothesis was to prove the assumption that to optimize the technology of development and obturation of root canals, tests of filling effectiveness are identified by the density and size of the gaps between the root canal wall, and the filling methods used and devices appropriate for material research, using mainly microscopy such as light stereoscopic (LSM) and scanning electron (SEM). The most beneficial preparations were obtained by making a longitudinal breakthrough of 48 natural human teeth, extracted for medical reasons, different from caries, with compliance with all ethical principles in this field. The teeth were prepared using various methods and filled with multiple obturation techniques, using a virtual selection of experimental variants. The breakthroughs were made in liquid nitrogen after a one-sided incision with a narrow gap created by a diamond disc using a materialographic cutter. The best effectiveness of the root canal filling was ensured by the technology of preparing the root canals with K3 rotary nitinol tools and filling the teeth with the THC thermoplastic method using the System B and Obtura III devices with studs and pellets of filling material based on gutta-percha after covering the root canal walls with a thin layer of AH Plus sealant. In this way, the research thesis was confirmed.

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Section: Methods and Tools Of Root Canal Preparation In Endodontic Treatmentmentioning

confidence: 99%

Is Gutta-Percha Still the “Gold Standard” among Filling Materials in Endodontic Treatment?

Dobrzańska¹,

Dobrzański²,

Dobrzański³

et al. 2021

Processes

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“…It has been known that the number of dislocations increases with increasing the amount of deformation [35]. Because more dislocations are produced in the BD3P sample, the back transformation to B2 is impeded, the stress feld area grows and more stable deformation can be obtained after training.…”

Section: Training and Two-way Shape Memory Efectmentioning

confidence: 99%

Effects of Predefined Thermomechanical Procedure on the Microstructure and Mechanical Properties of the Two-Way Shape Memory Effect in the NiTi Alloy

Tahaei

Aghajani

Abbasi

et al. 2023

Advances in Materials Science and Engineering

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In the current paper, a predefined thermomechanical procedure has been applied to the two-way shape memory effect (TWSME) in a NiTi alloy to study the effect of two different applied load conditions on the induced martensitic state. The microstructure of the strips was studied using optical microscopy (OM), scanning electron microscopy (SEM) fitted with an EDS microprobe, and microhardness tests at the end of both the training and thermal cycles. Inducing internal stresses along specified directions during training cycles results in the formation of oriented martensitic variants rather than expected twinned martensitic variants upon cooling. It was found that the microstructure is made up of interlocking martensitic lathes, including the fine martensite colony next to the coarse martensite lathes. Furthermore, the results of the average hardness tests for bending at one point and three points were 241 and 247 HV0.2, respectively. It was shown that only the cubic austenitic phase (B2) and the martensitic monoclinic phase (B19′) experience transformation. The results reveal that homogeneous bending in three locations leads to achieving the best difference between high- and low-temperature curvatures after training.

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“…HPT processing of NiTi alloys leads to a transformation from crystalline to amorphous phase. Microstructural changes in deformed NiTi during thermal treatment are of key interest as they are responsible for the shape memory effect [65,66]. During following thermal treatments nanocrystalline (NC) structure can be obtained in NiTi alloys via crystallization process (Figure 5) [64,67].…”

Section: Nanostructured Niti Shape Memory Alloysmentioning

confidence: 99%

“…Nanocrystalline NiTi alloys with grain size about 20 nm demonstrate very high strength up to 2000 MPa [64]. responsible for the shape memory effect [65,66]. During following thermal treatments nanocrystalline (NC) structure can be obtained in NiTi alloys via crystallization process (Figure 5) [64,67].…”

Section: Nanostructured Niti Shape Memory Alloysmentioning

confidence: 99%

Developing Nanostructured Ti Alloys for Innovative Implantable Medical Devices

et al. 2020

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Recent years have witnessed much progress in medical device manufacturing and the needs of the medical industry urges modern nanomaterials science to develop novel approaches for improving the properties of existing biomaterials. One of the ways to enhance the material properties is their nanostructuring by using severe plastic deformation (SPD) techniques. For medical devices, such properties include increased strength and fatigue life, and this determines nanostructured Ti and Ti alloys to be an excellent choice for the engineering of implants with improved design for orthopedics and dentistry. Various reported studies conducted in this field enable the fabrication of medical devices with enhanced functionality. This paper reviews recent development in the field of nanostructured Ti-based materials and provides examples of the use of ultra-fine grained Ti alloys in medicine.

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Grain Nucleation and Growth in Deformed NiTi Shape Memory Alloys: An In Situ TEM Study

Cited by 11 publications

References 67 publications

Is Gutta-Percha Still the “Gold Standard” among Filling Materials in Endodontic Treatment?

Is Gutta-Percha Still the “Gold Standard” among Filling Materials in Endodontic Treatment?

Effects of Predefined Thermomechanical Procedure on the Microstructure and Mechanical Properties of the Two-Way Shape Memory Effect in the NiTi Alloy

Developing Nanostructured Ti Alloys for Innovative Implantable Medical Devices

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