Determination of mechanical and functional properties by continuous vertical cast NiTi rod

Stambolić, Aleš; Jenko, M.; Kocijan, Aleksandra; Žužek, Borut; Drobne, Damjana; Rudolf, Rebeka

doi:10.17222/mit.2018.030

Cited by 6 publications

(5 citation statements)

References 22 publications

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“…Figure 1b shows the representative optical microstructures of the NiTi discs. The microstructure is typically a lamellar eutectic structure with phase composition: NiTi and Ni 3 Ti, which is consistent with previous research [26]. The bright phase is NiTi, containing around Ni = 50 at.% and Ti = 50 at.%, while the second darkminority phase is a eutectic phase composed of NiTi eut.…”

Section: Preparation Of Niti Discs For Microstructure Observationsupporting

confidence: 90%

Corrosion of NiTiDiscs in Different Seawater Environments

et al. 2022

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This paper gives an approach to the corrosion resistance analysis and changes in the chemical composition of anNiTi alloy in the shape of a disc, depending on different real seawater environments. The NiTi discs were analysed after 6 months of exposure in real seawater environments: the atmosphere, a tidal zone, and seawater. The corrosion tests showed that the highest corrosion rate for the discs is in seawater because this had the highest value of current density, and the initial disc had the most negative potential. Measuring the chemical composition of the discs using inductively coupled plasma and X-ray fluorescence before the experiment and semiquantitative analysis after the experiment showed the chemical composition after 6 months of exposure. Furthermore, the applied principal component analysis and cluster analysis revealed the influence of the different environments on the changes in the chemical composition of the discs. Cluster analysis detected small differences between the similar corrosive influences of the analysed types of environments during the period of exposure. The obtained results confirm that PCA can detect subtle quantitative differences among the corrosive influences of the types of marine environments, although the examined corrosive influences are quite similar. The applied chemometric methods (CA and PCA) are, therefore, sensitive enough to register the existence of slight differences among corrosive environmental influences on the analysed NiTi SMA.

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Section: Preparation Of Niti Discs For Microstructure Observationsupporting

confidence: 90%

Corrosion of NiTiDiscs in Different Seawater Environments

et al. 2022

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“…One of the main problems of SMAs is the possibility for further plastic deformation, especially cold drawing, due to the large grain size and existence of different brittle intermetallic phases. In order to overcome these two problems, a new processing technique was used, CC [12,13,14,15]. With the CC processing technique, the cast product can have a significantly smaller cross-section (as close as possible to the final dimension of the product), thus avoiding further plastic processing.…”

Section: Production Of Testing Sma Materialsmentioning

confidence: 99%

A Study of the Possible Use of Materials With Shape Memory Effect in Shipbuilding

Ivošević

Majerič

Vukičević

et al. 2020

JMTS

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The article presents a study of the possible use of materials with Shape Memory Effect (SME) in shipbuilding, which have two special abilities of transformation and changing shape with changing of temperature or deformation. Among the most well-known SME materials, our study focuses on Ni-Ti and Cu- based alloys. An example of the existing fabrication presents casting of Ni-Ti in the form of a disk, and a new approach – continuous casting of Ni-Ti and CuAlNi alloys in the form of rods. In the article some results are shown of characterisation of microstructure and the basic properties. This was done in accordance with the fact that such scientific approach could define the starting point for further identification of the functional characteristics of these alloys by knowing the their chemical content and microstructure. Numerous studies are being carried out today in order to find the optimal functional characteristics of SME alloys. All of this is aimed at optimising the fabrication of these alloys, with the achievement of suitable properties for application in shipbuilding.

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“…Nickel-titanium alloy was produced by vacuum induction melting (Leybold Hereaeus, Helsinki, Finland), followed by a novel continuous casting method (denoted as NiTi cc , composition 53.58 at.% of nickel, 46.42 at.% of titanium), with a laboratory scale vertical continuous casting (VCC) device (Technica Guss). Specifications of the laboratory VCC device are accessible in previous publications [21,22]. The corrosion behavior of continuous-cast alloy was compared with that of commercial nitinol (NiTi as cast, composition 50 at.% of nickel, 50 at.% of titanium, manufactured by the classical process, i.e., from remelting in a vacuum furnace with electro-resistive heating and final casting into ingots (Merkur d.d, Celje, Slovenija)).…”

Section: Processing Of the Samplesmentioning

confidence: 99%

Corrosion Behavior of Nickel–Titanium Continuous-Casted Alloys

Lazić,

Mitić,

Radović

et al. 2024

Metals

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Variations in the corrosion behavior of biomedical NiTi alloys in Cl− containing and acidic environments present a problem with their biological implantation. The objective of this research was to evaluate the synergy of the microstructure, the corrosion behavior, and the biocompatibility of novel continuous-cast NiTi alloys and to compare them with commercial NiTi alloys. The two alloys have a practically identical nominal chemical composition, but they differ in production technology. The continuous casting technology involved vacuum induction melting of the basic components and vertical continuous casting, while the commercial NiTi alloy was produced through a process of casting, hot rolling, and forming into square shapes. The microstructure was revealed to determine the surface area and size of grains. The corrosion of a commercial nickel–titanium alloy and one prepared by a novel continuous casting method in acidic and chloride-containing solutions was studied via analytical and electrochemical tests. Localized corrosion characteristics related to oxide properties, when exposed to 9 g L−1 NaCl solution, were examined with focused ion beam analysis and subsequent microchemical analysis of the formed corrosive products. Corrosion potential over time and the oxide film resistance were analyzed using linear polarization measurements. To obtain a preliminary estimate of biocompatibility, human fibroblast cells were used in indirect contact, i.e., alloy conditioning medium. The continuous casting method resulted in a reduction in the average grain size in comparison to the commercial sample and better corrosion stability of the sample in an acidic environment. Also, in a solution of 9 g L−1 NaCl the commercial sample showed high values for the corrosion current density (jcorr = 6 μA cm−2), which indicated low corrosion resistance, while the continuous casting sample possessed much better corrosion stability and lower values for the corrosion current density (jcorr = 0.2 μA cm−2). In line with that, elemental analysis of the corroded surfaces showed higher Cl− ion deposition over the surface layer of the commercial sample, suggesting local oxide breakdown. Moreover, NiTicc reached a value three times higher for polarization resistance (Rp = 270 kΩ cm2) over time in comparison to the commercial sample (Rp~100 kΩ cm2). Biocompatibility evaluation showed that human fibroblast cells exhibited altered metabolic activity. An MTT assay showed that cells’ mitochondrial activity dropped below that of control cells in the presence of both materials’ supernatants.

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Determination of mechanical and functional properties by continuous vertical cast NiTi rod

Cited by 6 publications

References 22 publications

Corrosion of NiTiDiscs in Different Seawater Environments

Corrosion of NiTiDiscs in Different Seawater Environments

A Study of the Possible Use of Materials With Shape Memory Effect in Shipbuilding

Corrosion Behavior of Nickel–Titanium Continuous-Casted Alloys

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