Effect of Nitrogen Addition on TiNi Shape Memory Alloys

2020 ◽  
Vol 12 (9) ◽  
pp. 1403-1408
Author(s):  
Izaz Ur Rehman ◽  
Tae-Hyun Nam
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Tensile Tests ◽  
Nitrogen Addition ◽  
Ternary Alloys ◽  
X Ray Diffraction ◽  
Transformation Temperatures ◽  
Arc Melting ◽  
Type Phase

In present paper we will show how nitrogen effects microstructures, transformation temperatures, and mechanical properties of equiatomic Ti50–Ni50 and Ti-rich Ti51–Ni49 binary shape memory alloys. 0.5 at.% of nitrogen was added to prepare Ti50–Ni49.5–N0.5, and Ti51–Ni48.5–N0.5 (at.%) alloys by arc-melting. Microstructures were investigated by scanning electron microscope (SEM), phase constitutions were investigated by X-ray diffraction (XRD), transformation temperatures were investigated by differential scanning calorimeter (DSC) and mechanical properties were tested by tensile tests. Solutions treated Ti–Ni–N shape memory alloys contain TiNi matrix without nitrogen, Ti2Ni type phase containing a small amount of nitrogen and a new Ti2N type phase containing a small amount of nickel. Compared with Ti50–Ni50 and Ti51–Ni49 binary alloys, the martensitic transformation starts temperatures (Ms) of Ti50–Ni49.5–N0.5 and Ti51–Ni48.5–N0.5 ternary alloys decreased from 63.4 °C to 41.6 °C and from 85.3 °C to 79.4 °C, respectively. By adding N, fracture strain decreased and incomplete superelasticity was observed.

Effect of Nitrogen Addition on Mechanical Property of Ti-Cr-Sn Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2126-2129 ◽  
Author(s):  
Yuichi Nakahira ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Shuichi Miyazaki ◽  
Hideki Hosoda
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Nitrogen Addition ◽  
N Addition ◽  
X Ray Diffraction ◽  
Solution Hardening ◽  
X Ray ◽  
Bcc Phase ◽  
Cold Workability

Effect of nitrogen (N) addition on mechanical properties of Ti-Cr-Sn alloy was investigated in this study. Ti-7mol%Cr-3mol%Sn was selected and less than 0.5wt% of N were systematically added. The alloys were characterized by optical microscopy, X-ray diffraction analysis and tensile tests at room temperature. The apparent phase was β (bcc) phase, whereas the presence of precipitates was confirmed in 0.5wt%N-added alloy only which did not exhibit sufficient cold workability. The grain size was not largely affected by N addition being less than 0.5wt%. Tensile tests revealed that less than 0.5wt%N addition improves the strength which is due to the solution hardening by interstitial N atoms.

Property Improvement of TiNi by Cu Addition for Orthodontics Applications

2011 ◽  
Vol 87 ◽  
pp. 95-100 ◽  
Author(s):  
A. Phukaoluan ◽  
Anak Khantachawana ◽  
Pongpan Kaewtatip ◽  
Surachai Dechkunakorn ◽  
N. Anuwongnukroh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Internal Stress ◽  
Thin Plates ◽  
Orthodontic Wires ◽  
Transformation Temperatures ◽  
Cu Content ◽  
Ni Content ◽  
Heat Treated

This study aims to investigate mechanical properties and transformation behavior of TiNiCu shape memory alloys to obtain optimal conditions for utilizing as orthodontic wires. TiNi binary alloys with Ni-content 50.6 at.%, TiNiCu alloys with Cu-content ranging from 5 to 10 at.% were prepared. The alloys were melted by electrical arc-melting method and then homogenized at 800°C for 3600 s. The alloys were subsequently sliced into thin plates (1.5 mm) by EDM wire cutting machine. To evaluate mechanical properties, the specimens were cold-rolled with 10, 20 and 30%, followed by heat treatment at 400°C and 600°C for 3600 s, respectively. A Differential Scanning Calorimeter (DSC) was used to detect transformation temperatures. Mechanical properties were evaluated by micro hardness and three-point bending tests. The results showed that transformation temperatures were strongly increased with increasing Ni-content. Moreover, the decrease in transformation temperature after increasing level of cold-rolling reduction ratio suggests that internal stress can depress transformation. However, internal stress seemed to support the introduction of superelasticity for each specimen. In addition, specimens heat treated at 400°C have, more appropriate properties as orthodontic wires than those heat-treated at 600°C due to the remaining effect of cold-working. These results can be take into consideration for optimizing alloy composition and mechanical properties of TiNiCu shape memory alloys for orthodontics wires purposes.

Effect of Aging on Microstructure and Martensitic Transformation in Ti-Zr-Ni Shape Memory Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 3163-3168 ◽  
Author(s):  
Adrian Sandu ◽  
Koichi Tsuchiya ◽  
Shinya Yamamoto ◽  
Masayuki Tabuchi ◽  
Yoshikazu Todaka ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Vickers Hardness ◽  
Isothermal Aging ◽  
Transformation Temperatures ◽  
Second Stage ◽  
Stage Process

Effect of isothermal aging on martensitic transformation temperatures, mechanical properties and microstructure was investigated for a Ni-rich Ti-Zr-Ni shape memory alloy at temperatures ranging from 673 K to 773 K. The aging behaviour was two stage process: the first stage associated with an increase in the Vickers hardness and a decrease in martensitic transformation temperatures and the second stage with a decrease in the hardness and increase in the transformation temperatures. Second stage was also characterized by the appearance of nano-scale precipitates, which has never been reported.

Effect of Nb Content on Superelastic Properties of Biomedical Ti–Zr-Based Shape Memory Alloys

2020 ◽  
Vol 12 (9) ◽  
pp. 1394-1398
Author(s):  
Shuanglei Li ◽  
Mi-Seon Choi ◽  
Tae-Hyun Nam
Keyword(s):  
Tensile Test ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Nb Content

Ti–18Zr–xNb–2Sn (x = 10, 11, 11.5, 12, 12.5) (at.%) shape memory alloys were fabricated by arc melting then phase constitutions and superelastic properties were investigated by X-ray diffraction (XRD) and tensile test at various temperatures between 178 K and 413 K. Excellent superelasticity was observed in 12.5Nb alloy at temperatures between 258 K and 298 K. Both superelasticity and shape memory effect were observed in 12Nb alloy at temperatures between 233 K and 383 K. Only shape memory effect was observed in 11Nb and 11.5Nb alloys at temperatures between 298 K and 383 K. 12.5Nb and 12Nb alloys consisted of the main β phase and athermal ω. The amount of β phase decreased with increasing Nb content. 10Nb alloy consisted of main α″ martensite and a small amount of β phase. The Ms temperature measured from the Clausius–Clapeyron relationship decreased greatly with increasing Nb content (100 K/at.% Nb) in these Ti–Zr–Nb–Sn alloys.

Effect of Microstructure on Mechanical Properties of Ti-Al Based Alloys

2011 ◽  
Vol 675-677 ◽  
pp. 709-712
Author(s):  
Xiao Fei Ding ◽  
Y. Tan ◽  
Bao Qing Zeng
Keyword(s):  
Mechanical Properties ◽  
Lamellar Microstructure ◽  
Tensile Tests ◽  
Ternary Alloys ◽  
Electron Probe Microanalyzer ◽  
Multiple Phase ◽  
Arc Melting ◽  
Increasing Temperature ◽  
Α2 Phase ◽  
Better Than

Three types of TiAl-Nb ternary alloys are obtained by arc-melting and heat treatment, which are γ-TiAl single phase, γ-TiAl + α2-Ti3Al duplex phase and γ-TiAl +α2-Ti3Al +Nb2Al multiple phase alloy. The phase stability is studied using X-ray diffractometer and electron probe microanalyzer. Mechanical properties are investigated through compress and tensile tests at RT to 1373K. It is found that, their mechanical properties are related to their microstructures. The deformability of alloy B is better than that of alloy A and C at RT due to small grain size reduced by α2 phase appearance, lamellar microstructure and interfaces. The deformability of alloy B increases significantly with increasing temperature, the elongation of alloy B achieves 40.4% at 1173K. The fracture mode of alloy B changed from brittle transgranular failure at room temperature to ductile intergranular failure at 1173K. While, both of alloy A and C have not increased its deformability at 1173K and showed brittle transgranular failure at both temperatures. Alloy C was a very brittle material at room and high temperature due to Nb2Al phase appearance, which reducing the continuity of (γ+α2) lamellar structure.

Phase Transformation and Shape Memory Effect in Ru-Based High Temperature Shape Memory Alloys

2011 ◽  
Vol 172-174 ◽  
pp. 43-48 ◽  
Author(s):  
Anna Manzoni ◽  
Karine Chastaing ◽  
Anne Denquin ◽  
Philippe Vermaut ◽  
Richard Portier
Keyword(s):  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Binary Alloys ◽  
Quantitative Result ◽  
Lattice Parameters ◽  
Ternary Alloys ◽  
Transformation Temperatures

Among the different systems for high temperature shape memory alloys (SMA’s), equiatomic RuNb and RuTa alloys demonstrate both shape memory effect (SME) and MT temperatures above 800°C. For both systems, it is interesting to find a way to control the transformation temperatures while keeping the shape memory effect. One way to change the transformation temperatures is to change the composition in the binary alloys; another is to add a ternary element like Fe. The eight investigated alloys show two different space groups at room temperature. The monoclinic alloys undergo two successive displacive transformations on cooling, starting from the high temperature β phase field: β (B2) à β’ (tetragonal) à β’’ (monoclinic). The tetragonal alloys exhibit a single transition from cubic to tetragonal. A multiple twinned microstructure can be found in all alloys. Transformation temperatures decrease with lower Ru content and with the addition of Fe. The β’ à β transformation seems to be the main responsible for the SME. Compression tests performed in the martensitic phase give a quantitative result of the shape memory effect. In the binary alloys, the SME decreases with decreasing Ru content, which is in accordance with the evolution of the lattice parameters of martensites. A lower SME in the ternary alloys can also be linked to the lattice parameters and seems to be quite reliable to predict the evolution of the shape memory effect.

scholarly journals Effect of Crystallographic Orientation and Grain Boundaries on Martensitic Transformation and Superelastic Response of Oligocrystalline Fe–Mn–Al–Ni Shape Memory Alloys

2021 ◽  
Author(s):  
A. Bauer ◽  
M. Vollmer ◽  
T. Niendorf
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundary ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grain Boundaries ◽  
Tensile Tests ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Grain Orientations ◽  
High Degree

AbstractIn situ tensile tests employing digital image correlation were conducted to study the martensitic transformation of oligocrystalline Fe–Mn–Al–Ni shape memory alloys in depth. The influence of different grain orientations, i.e., near-〈001〉 and near-〈101〉, as well as the influence of different grain boundary misorientations are in focus of the present work. The results reveal that the reversibility of the martensite strongly depends on the type of martensitic evolving, i.e., twinned or detwinned. Furthermore, it is shown that grain boundaries lead to stress concentrations and, thus, to formation of unfavored martensite variants. Moreover, some martensite plates seem to penetrate the grain boundaries resulting in a high degree of irreversibility in this area. However, after a stable microstructural configuration is established in direct vicinity of the grain boundary, the transformation begins inside the neighboring grains eventually leading to a sequential transformation of all grains involved.

Improvement of Mechanical Properties of Powder Metallurgical NiTi Shape Memory Alloys

2006 ◽  
Vol 8 (4) ◽  
pp. 247-252 ◽  
Author(s):  
J. Mentz ◽  
M. Bram ◽  
H. P. Buchkremer ◽  
D. Stöver
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Niti Shape Memory Alloys
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