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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Reversible phase transformations in a shape memory alloy In–Tl nanowires observed by in situ transmission electron microscopy

Materials Letters ◽

10.1016/j.matlet.2011.11.049 ◽

2012 ◽

Vol 70 ◽

pp. 109-112 ◽

Cited By ~ 7

Author(s):

Hongxing Zheng ◽

Zhiping Luo ◽

Dong Fang ◽

Francis R. Phillips ◽

Dimitris C. Lagoudas

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Shape Memory Alloy ◽

Shape Memory ◽

Phase Transformations ◽

Transmission Electron ◽

Reversible Phase

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Stress-induced martensitic transformations in a Cu–Al–Ni shape memory alloy studied by in situ transmission electron microscopy

Materials Science and Engineering A ◽

10.1016/j.msea.2006.12.208 ◽

2008 ◽

Vol 481-482 ◽

pp. 457-461 ◽

Cited By ~ 17

Author(s):

N. Zárubová ◽

J. Gemperlová ◽

V. Gärtnerová ◽

A. Gemperle

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Shape Memory Alloy ◽

Shape Memory ◽

Martensitic Transformations ◽

Transmission Electron

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In situ Transmission Electron Microscopy and Nanoindentation Studies of Phase Transformation and Pseudoelasticity of Shape-memory Titanium-nickel Films

Journal of Materials Research ◽

10.1557/jmr.2005.0226 ◽

2005 ◽

Vol 20 (7) ◽

pp. 1808-1813 ◽

Cited By ~ 22

Author(s):

X.-G. Ma ◽

K. Komvopoulos

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Phase Transformation ◽

Shape Memory ◽

Heating And Cooling ◽

Transmission Electron ◽

Different Temperatures ◽

Titanium Nickel ◽

In Situ Heating

Transmission electron microscopy (TEM) and nanoindentation, both with in situ heating capability, and electrical resistivity measurements were used to investigate phase transformation phenomena and thermomechanical behavior of shape-memory titanium-nickel (TiNi) films. The mechanisms responsible for phase transformation in the nearly equiatomic TiNi films were revealed by heating and cooling the samples inside the TEM vacuum chamber. Insight into the deformation behavior of the TiNi films was obtained from the nanoindentation response at different temperatures. A transition from elastic-plastic to pseudoelastic deformation of the martensitic TiNi films was encountered during indentation and heating. In contrast to the traditional belief, the martensitic TiNi films exhibited a pseudoelastic behavior during nanoindentation within a specific temperature range. This unexpected behavior is interpreted in terms of the evolution of martensitic variants and changes in the mobility of the twinned structures in the martensitic TiNi films, observed with the TEM during in situ heating.

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

Materials ◽

10.3390/ma14164455 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4455

Author(s):

Pedro Cunha Lima ◽

Patrícia Freitas Rodrigues ◽

Ana Sofia Ramos ◽

José D. M. da Costa ◽

Francisco Manuel Braz Fernandes ◽

...

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Low Cycle Fatigue ◽

Niti Alloy ◽

Niti Shape Memory Alloy ◽

Cycle Fatigue ◽

Maximum Deformation ◽

Transmission Electron ◽

Before And After

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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