In Situ TEM Observation of Phase Transformation for Bio-Medical Shape Memory TiNbSn Alloy

2010 ◽  
Vol 152-153 ◽  
pp. 1755-1758
Author(s):  
Yan Li ◽  
Jie Qi ◽  
Rui Rui Fan ◽  
Chuan Xin Zhai ◽  
Chun Hua Xu
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Shape Memory ◽  
Martensite Phase ◽  
Unit Cell ◽  
Niti Shape Memory Alloy ◽  
Transformation Mechanism ◽  
Cell Parameters ◽  
Β Phase

TiNbSn alloy has high specific strength, low modulus of elasticity, excellent corrosion resistance, no side effects, such as toxic and exhibits shape memory effects after appropriate technical processing. This alloy may substitute as NiTi shape memory alloy to become the new generation of biological materials. It has been reported the studies of this alloy, such as the component and proportion, processing technology, mechanical properties and corrosion resistance. Based on the previous research, the bio-metal material, Ti-10Nb-5Sn alloy was heated and cooled repeatedly in a heater system located in TEM chamber and, at the same time, was observed in situ using a high resolution transmission electron microscope to study the memory property of the alloy and the mechanism of the transformation between austenite β and martensite phase. The results show that, during heating stage from 295K to 400K, the martensite began to dissolve at 355K, and the martensite disappeared completely at 385K, meanwhile, the austenite was created. During cooling stage from 400K to 295K, the martensite begins to take shape at 353K and the transformation was completed at 333K. The alloy can memory the room and high temperature structures, showing two-way memory functions. The high-temperature austenite of Ti-10Nb-5Sn alloy shows body-centered cubic β phase with the unit cell parameter a=0.3283nm; the martensite at room temperature shows orthorhombic NbTi4 phase (M) with the unit cell parameters a=0.3152nm, b=0.4854nm, c=0.4642nm. The orientation relationship between M phase and β phase is , , , , and . The crystal plane , as the habit plane, transforms into during the transformation from β to M phases. The martensite transformation mechanism is that the and transform to and through the tiny migration of atoms.

scholarly journals In situ high-temperature behaviour of fluor-elbaite: breakdown conditions and products

2021 ◽  
Vol 48 (6) ◽  
Author(s):  
Beatrice Celata ◽  
Paolo Ballirano ◽  
Giovanni B. Andreozzi ◽  
Ferdinando Bosi
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Structural Parameters ◽  
Unit Cell ◽  
Temperature Behaviour ◽  
Unit Cell Parameters ◽  
Thermally Induced ◽  
X Ray ◽  
Cell Parameters

AbstractThe thermal behaviour of a fluor-elbaite from Minas Gerais (Brazil) was investigated at room pressure through in situ high-temperature X-ray powder diffraction (HT-XRPD), until the breakdown conditions were reached. The variations of fluor-elbaite structural parameters (unit-cell parameters and mean bond distances) were monitored together with site occupancies, and two main internal reactions were identified: the thermally-induced Fe oxidation process counterbalanced by (OH)– deprotonation, which starts at 500 °C (773 K), followed by a partial intracrystalline Fe–Al exchange between the octahedrally-coordinated Y and Z sites. The fluor-elbaite breakdown reaction occurs between 850 °C (1123 K) and 900 °C (1173 K). The breakdown products were identified at room temperature by XRPD and the breakdown reaction can be described by the following reaction: tourmaline → B-bearing mullite + hematite + spinel + B-poor (Na, Li, H2O)-bearing glass. Boromullite itself was not observed in the final heating products, and the B-bearing mullite from the breakdown reaction exhibited unit-cell parameters a = 7.5382(2) Å, b = 7.6749(2) Å, c = 2.8385(1) Å, V = 164.22(1) Å3 (space group Pbam) consistent with an approximate Al8.5B1.5Si2O19 composition.

Effect of Titanium Depletion of High Temperature Treated NiTi Shape Memory Alloy Wire

2013 ◽  
Vol 467 ◽  
pp. 70-75
Author(s):  
Nazihah Nawawi ◽  
Abdus Samad Mahmud
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Heating Temperature ◽  
Temperature Treatment ◽  
Martensite Phase ◽  
High Temperature Treatment ◽  
Niti Shape Memory Alloy ◽  
Volume Percentage ◽  
Outward Diffusion ◽  
The Matrix

Shape memory behaviour of NiTi is very sensitive to the presence of inclusion in the matrix and oxide and the surface. This work studied the influence of high temperature treatment towards thermal martensitic transformation behaviour of NiTi. The alloy was subjected to heat treatment at 1223 K for various times in argon and air environment. It was found that treatment in air severely destroyed the shape memory property of the alloy due to the formation of multilayer of oxides. Treatment in argon also reduced the volume percentage of martensite phase transformation, even though no oxide layer was observed at the surface. This reduction is caused by the depletion of Ti element in the matrix due to the outward diffusion of Ti element. The outward diffusion of Ti is however stabilized at 15 hours exposure time of 1223 K heating temperature.

In Situ High Temperature Texture Characterisation in NiTi Shape Memory Alloy Using Synchrotron Radiation

2005 ◽  
pp. 125-130
Author(s):  
Andersan S. Paula ◽  
Karimbi K. Mahesh ◽  
Francisco Manuel Braz Fernandes ◽  
Rui Miguel S. Martins ◽  
A.M.A. Cardoso ◽  
...  
Keyword(s):  
High Temperature ◽  
Synchrotron Radiation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy

Analyses of Phase Transformation Mechanism Based on In Situ Observation during Ti-10Nb-5Sn Alloy Heating Cycles

2012 ◽  
Vol 549 ◽  
pp. 535-538
Author(s):  
Yan Li ◽  
Jie Qi ◽  
Chuan Xin Zhai ◽  
Ran Feng Qiu
Keyword(s):  
Phase Transformation ◽  
Electron Microscope ◽  
Shape Memory ◽  
Transmission Electron Microscope ◽  
Memory Function ◽  
Martensite Phase ◽  
Round Trip ◽  
Transformation Mechanism ◽  
Transmission Electron

The Ti-10Nb-5Sn alloy was heated and cooled repeatedly in a heater system located in transmission electron microscope chamber. The phase and morphology transformation was in situ observed to analyze the transformation mechanism from austenite β to martensite phase. The results reveal that he Ti-10Nb-5Sn alloy has round trip shape memory function.

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

2014 ◽  
Vol 81 ◽  
pp. 4-7 ◽  
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

High-temperature diffraction experiments and phase diagram of ZrO2 and ZrSiO4

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Akira Yoshiasa ◽  
Tsubasa Tobase ◽  
Hiroshi Arima-Osonoi ◽  
Ken-Ichi Funakoshi ◽  
Osamu Ohtaka ◽  
...  
Keyword(s):  
High Temperature ◽  
Unit Cell ◽  
Cubic Phase ◽  
Imaging Plate ◽  
X Ray Diffraction ◽  
Space Group ◽  
Cell Parameters ◽  
Time Observation ◽  
Short Time ◽  
Clear Change

Abstract High-temperature X-ray diffraction (XRD) experiments up to T = 2710 °C have been performed on ZrSiO4 and ZrO2 powders, using the container-less levitation technique. A two-dimensional imaging plate (IP) detector was used for short-time observation. The diffraction data in a wide area was projected in one dimension. The unit cell parameters, thermal expansions, and c/a ratios for ZrSiO4 (space group I41/amd and Z = 4), tetragonal ZrO2 (space group P42/nmc and Z = 2) and cubic ZrO2 (space group  F m 3   ‾ m $Fm3‾{}m$ and Z = 4) were measured to understand the high-temperature behaviors. The transition temperature between tetragonal and cubic ZrO2 was specified to be between 2430 and 2540 °C. The pre-transitional behavior was observed around 2200 °C. As no clear change in unit cell volume is evident, the phase boundary between the tetragonal and the cubic phase has been shown to be a positive slope. The ZrO2 and ZrO2–SiO2 phase diagrams are proposed based on the chemical composition and the crystal structure.

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