Experimental Analysis of NiTi Alloy during Strain-Controlled Low-Cycle Fatigue

The interaction between the stress-induced martensitic transformation and resistivity behavior of superelastic NiTi shape memory alloy (SMA) was studied. Strain-controlled low-cycle fatigue up to 6% was monitored by in situ electrical resistivity measurements. The experimental results show that a great motion of martensite fronts results in a significant accumulation of defects, as evidenced by transmission electron microscopy (TEM), before and after the tensile cycles. This gives rise to an overall increase of the resistivity values up to the maximum deformation. Therefore, the research suggests that shape memory alloy wire has great potential as a stress sensor inside bulk materials.

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Multiaxial low-cycle fatigue failure mechanism of super-elastic NiTi shape memory alloy micro-tubes

Materials Science and Engineering A ◽

10.1016/j.msea.2016.04.019 ◽

2016 ◽

Vol 665 ◽

pp. 17-25 ◽

Cited By ~ 11

Author(s):

Di Song ◽

Guozheng Kang ◽

Qianhua Kan ◽

Chao Yu ◽

Chuanzeng Zhang

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Failure Mechanism ◽

Fatigue Failure ◽

Low Cycle Fatigue ◽

Niti Shape Memory Alloy ◽

Cycle Fatigue

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Observation of Phase Transformation in Shape Memory Alloy NiTi Wire during In Vitro Simulation of Orthodontic Treatment

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.364.61 ◽

2015 ◽

Vol 364 ◽

pp. 61-70

Author(s):

Rebeka Rudolf ◽

Janko Ferčec

Keyword(s):

Electron Microscopy ◽

Phase Transformation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Electrical Resistance ◽

Orthodontic Treatment ◽

Niti Shape Memory Alloy ◽

Niti Wire ◽

Transmission Electron

The aim of this study was to simulate the different loadings on NiTi Shape Memory Alloy in the form of wire that occurs in orthodontic praxis. Our main goals were to detect and determine the beginning of the stress-induced transformation from the austenite to martensite phases and to indicate the transformation plateau at different deformations during orthodontic treatment usingin-vitrosimulation. For this reason, we developed two prototype devices forin-situsimulation of orthodontic treatment by which we measured the electrical resistance and hardness. Accompanying these two properties and the microstructure observations of loaded wires by Transmission Electron Microscopy enabled us to detect successfully the stabilized stress-induced martensite due phase transformation. We found out that transformation depends strongly on the type of loading.

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Key Properties of a Bioactive Ag-SiO2/TiO2 Coating on NiTi Shape Memory Alloy as Necessary at the Development of a New Class of Biomedical Materials

International Journal of Molecular Sciences ◽

10.3390/ijms22020507 ◽

2021 ◽

Vol 22 (2) ◽

pp. 507

Author(s):

Mateusz Dulski ◽

Robert Gawecki ◽

Sławomir Sułowicz ◽

Michal Cichomski ◽

Alicja Kazek-Kęsik ◽

...

Keyword(s):

Surface Roughness ◽

Shape Memory Alloy ◽

Shape Memory ◽

Dermal Fibroblast ◽

Niti Alloy ◽

Bacterial Biofilm ◽

Niti Shape Memory Alloy ◽

Normal Human Dermal Fibroblast ◽

Water Contact ◽

Nano Coating

Recent years have seen the dynamic development of methods for functionalizing the surface of implants using biomaterials that can mimic the physical and mechanical nature of native tissue, prevent the formation of bacterial biofilm, promote osteoconduction, and have the ability to sustain cell proliferation. One of the concepts for achieving this goal, which is presented in this work, is to functionalize the surface of NiTi shape memory alloy by an atypical glass-like nanocomposite that consists of SiO2-TiO2 with silver nanoparticles. However, determining the potential medical uses of bio(nano)coating prepared in this way requires an analysis of its surface roughness, tribology, or wettability, especially in the context of the commonly used reference coat-forming hydroxyapatite (HAp). According to our results, the surface roughness ranged between (112 ± 3) nm (Ag-SiO2)—(141 ± 5) nm (HAp), the water contact angle was in the range (74.8 ± 1.6)° (Ag-SiO2)—(70.6 ± 1.2)° (HAp), while the surface free energy was in the range of 45.4 mJ/m2 (Ag-SiO2)—46.8 mJ/m2 (HAp). The adhesive force and friction coefficient were determined to be 1.04 (Ag-SiO2)—1.14 (HAp) and 0.247 ± 0.012 (Ag-SiO2) and 0.397 ± 0.034 (HAp), respectively. The chemical data showed that the release of the metal, mainly Ni from the covered NiTi substrate or Ag from Ag-SiO2 coating had a negligible effect. It was revealed that the NiTi alloy that was coated with Ag-SiO2 did not favor the formation of E. coli or S. aureus biofilm compared to the HAp-coated alloy. Moreover, both approaches to surface functionalization indicated good viability of the normal human dermal fibroblast and osteoblast cells and confirmed the high osteoconductive features of the biomaterial. The similarities of both types of coat-forming materials indicate an excellent potential of the silver-silica composite as a new material for the functionalization of the surface of a biomaterial and the development of a new type of functionalized implants.

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An in situ TEM study of the size effect on the thermally induced martensitic transformation in nanoscale NiTi shape memory alloy

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2013.11.119 ◽

2014 ◽

Vol 588 ◽

pp. 337-342 ◽

Cited By ~ 16

Author(s):

H.X. Li ◽

S.C. Mao ◽

K.T. Zang ◽

Y. Liu ◽

Z.X. Guo ◽

...

Keyword(s):

Martensitic Transformation ◽

Shape Memory Alloy ◽

Size Effect ◽

Shape Memory ◽

Niti Shape Memory Alloy ◽

In Situ Tem ◽

Thermally Induced

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In situ W–NiTi shape memory alloy composite of high radiopacity

Scripta Materialia ◽

10.1016/j.scriptamat.2014.02.002 ◽

2014 ◽

Vol 81 ◽

pp. 4-7 ◽

Cited By ~ 10

Author(s):

S. Wang ◽

F.M. Guo ◽

D.Q. Jiang ◽

Y. Liu ◽

L.S. Cui

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Niti Shape Memory Alloy ◽

Alloy Composite

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Load Partition in NiTi Shape Memory Alloy Polycrystals Investigated by In-Situ Neutron Diffraction and Micromechanics Modelling

Materials Science Forum ◽

10.4028/www.scientific.net/msf.404-407.829 ◽

2002 ◽

Vol 404-407 ◽

pp. 829-834 ◽

Cited By ~ 4

Author(s):

Petr Šittner ◽

Václav Novák ◽

Petr Lukáš ◽

D. Lugovyy ◽

D. Neov ◽

...

Keyword(s):

Neutron Diffraction ◽

Shape Memory Alloy ◽

Shape Memory ◽

Niti Shape Memory Alloy ◽

In Situ Neutron Diffraction

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EFFECTS OF PARTICLE SIZE AND SINTERING TEMPERATURE ON SUPERELASTICITY BEHAVIOR OF NiTi SHAPE MEMORY ALLOY USING NANOINDENTATION

Surface Review and Letters ◽

10.1142/s0218625x21500244 ◽

2021 ◽

pp. 2150024

Author(s):

C. VELMURUGAN ◽

V. SENTHILKUMAR

Keyword(s):

Particle Size ◽

Shape Memory Alloy ◽

Shape Memory ◽

Sintering Temperature ◽

Niti Alloy ◽

Indentation Load ◽

Niti Shape Memory Alloy ◽

Recovery Ratio ◽

Work Recovery ◽

Niti Sma

The present study investigates the superelasticity properties of spark plasma sintered (SPS) nickel titanium shape memory alloy (NiTi SMA) with the influence of sintering temperature and particle size. The nanoindentation is conducted on the surface of the NiTi SMA at various loads such as 100, 300 and 500[Formula: see text]mN. The nanoindentation technique determines the quantitative results of elasto-plastic properties such as depth recovery in the form of superelasticity, stiffness, hardness and work recovery ratio from load–depth ([Formula: see text]–[Formula: see text]) data during loading and unloading of the indenter. Experimental findings show that the depth and work recovery ratio increases with the decrease of indentation load and particle size. In contrast, increasing the sintering temperature exhibited a better depth and work recovery due to the removal of pores which could enhance the reverse transformation. The contact stiffness is influenced by [Formula: see text] which leads to attain a maximum stiffness at the highest load (500[Formula: see text]mN) and particle size (45[Formula: see text][Formula: see text]m) along with the lowest sintering temperature (700∘C). NiTi alloy exhibited a maximum hardness of 9.46[Formula: see text]GPa when subjected to indent at the lowest load and particle size sintered at 800∘C. The present study reveals a better superelastic behavior in NiTi SMA by reducing the particle size and indentation load associated with the enhancement of sintering temperature.

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Biocompatibility of Nanoporous TiO2Coating on NiTi Alloy Prepared via Dealloying Method

Journal of Nanomaterials ◽

10.1155/2012/731592 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Jin Huang ◽

Junqiang Wang ◽

Xiangdong Su ◽

Weichang Hao ◽

Tianmin Wang ◽

...

Keyword(s):

Low Temperature ◽

Shape Memory ◽

Biomedical Application ◽

Niti Alloy ◽

Treatment Method ◽

Niti Shape Memory Alloy ◽

Contact Method ◽

Biological Compatibility ◽

Before And After ◽

Niti Shape Memory Alloys

This paper investigated the biocompatibility of nanoporous TiO2coating on NiTi shape-memory alloy (SMA) prepared via dealloying method. Our previous study shows that the dealloying treatment at low temperature leads to 130 nm Ni-free surface titania surface layer, which possesses good bioactivity because of the combination of hydroxyl (OH−) group in the process of dealloying treatment simultaneously. In this paper, the biological compatibility of NiTi alloy before and after dealloying treatment was evaluated and compared by direct contact method with dermal mesenchymal stem cells (DMSCs) by the isolated culture way. The interrelation between the biological compatibility and surface change of material after modification was systematically analyzed. As a consequence, the dealloying treatment method at low temperature could be of interest for biomedical application, as it can avoid sensitization and allergies and improve biocompatibility of NiTi shape-memory alloys. Thus it laid the foundation of the clinical trials for surface modification of NiTi memory alloy.

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