Martensitic Transformation of TiAu Shape Memory Alloys

2007 ◽  
Vol 561-565 ◽  
pp. 1541-1544 ◽  
Author(s):  
Hideki Hosoda ◽  
Ryosuke Tachi ◽  
Tomonari Inamura ◽  
Kenji Wakashima ◽  
Shuichi Miyazaki
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Parent Phase ◽  
Stoichiometric Composition ◽  
Transformation Strain ◽  
Martensite Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Rich Side

Martensitic transformation temperatures were measured and transformation strains were evaluated in a promising high temperature shape memory alloy TiAu with a compositional range from 46 to 53mol%Au. It was found by differential scanning calorimetry that martensitic transformation start temperature (Ms) is kept almost constant value of 880K in the Au-rich side of the stoichiometric composition. On the other hand, Ms decreases monotonically with decreasing Au content in the Au-poor side. X-ray diffraction analysis revealed that apparent phase of all the alloys at room temperature is B19 martensite phase. Under an assumption that the atomic volume is constant during martensitic transformation, the lattice parameters of B2 parent phase and maximum transformation strain were calculated. It was found that the maximum transformation strain depends on chemical composition and that it reaches 10.75% for Ti-53mol%Au alloy. The value is comparable to that of Ti-Ni.

Martensitic Transformation and Related Properties of AuTi-FeTi Pseudobinary Alloys

2014 ◽  
Vol 922 ◽  
pp. 25-30 ◽  
Author(s):  
Taku Aoki ◽  
Masaki Tahara ◽  
Kenji Goto ◽  
Yoko Yamabe-Mitarai ◽  
Hiroyasu Kanetaka ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Parent Phase ◽  
Tensile Tests ◽  
Martensite Phase ◽  
Lattice Deformation ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Fe Content ◽  
Fe Addition

The effects of Fe addition on martensitic transformation and mechanical properties of AuTi were investigated in this study. It was found that B2 parent phase is stabilized by the Fe addition and that AuTi can contain at least 20mol%Fe. The lattice deformation strain evaluated from θ-2θ X-ray diffraction analysis (XRD) is not significantly changed by the Fe addition. The decrease in Ms evaluated by differential scanning calorimetry (DSC) is-40K/mol%Fe. Tensile tests revealed that, with increasing Fe content, the yield stress decreases up to about 13mol%Fe, largely increases up to 15mol%Fe and then decreases gradually. By taking into account XRD and DSC results, these behaviors are judged to correspond to reorientation of martensite variants, stress induced martensitic transformation and slip deformation of parent phase, respectively. The values of dσSIMT/dCFe and dσSIMT/dT are evaluated to be-170MPa/mol%Fe and-4.3MPa/K, respectively. The elongation is degraded with increasing Fe content from 8% in AuTi (0mol%Fe, martensite phase) to 2% in AuTi-20mol%Fe (parent phase) depending on the apparent phase.

Martensitic Transformation and Shape Memory Effect of Ni53.25Mn21.75Ga25 Ferromagnetic Shape Memory Alloy

2012 ◽  
Vol 476-478 ◽  
pp. 1504-1507
Author(s):  
Hai Bo Wang ◽  
Shang Shen Feng ◽  
Pei Yang Cai ◽  
Yan Qiu Huo
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Parent Phase ◽  
Transformation Strain ◽  
Scanning Calorimetry ◽  
Reversible Transformation ◽  
Ferromagnetic Shape Memory

The martensitic transformation, crystalline structure, microstructure and shape memory effect of the Ni53.25Mn21.75Ga25 (at.%) alloy are investigated by means of Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and the standard metal strain gauge technique. The XRD results showed that the Ni53.25Mn21.75Ga25 alloy is composed of cubic parent phase at room temperature. TEM observation proved that the typical twin martensite is tetragonal structure and tweed-like contrast which is typical image for the parent phase. A large reversible transformation strain, about 0.54%, is obtained in this undeformed polycrystalline alloy due to martensitic transformation and its reverse transformation. This transformation strain is also increased to 0.65% by the external magnetic field. It is believed that the effect of the magnetic field on the preferential orientation of martensitic variants increases the transformation strain.

scholarly journals Nanocrystal, phase transformation and microstructure of Ni50Ti50 shape memory alloy

2018 ◽  
Vol 24 (02) ◽  
pp. 22-25
Author(s):  
Dovchinvanchig M ◽  
Chunwang Zhao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
One Step ◽  
Niti Matrix ◽  
Electronic Microscope

The nanocrystal, phase transformation and microstructure behavior of Ni50Ti50 shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results showed that the microstructure of Ni-Ti binary alloy consists of the NiTi2 phase and the NiTi matrix phase. One-step phase transformation was observed alloy.

Characterization of the Phase Transformations in the Shape Memory Alloy Ni-36 at.% Al

1991 ◽  
Vol 246 ◽  
Author(s):  
J.A. Horton ◽  
E.P. George ◽  
C.J. Sparks ◽  
M.Y. Kao ◽  
O.B. Cavin ◽  
...  
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Phase Transformations ◽  
Hot Extrusion ◽  
Exothermic Peak ◽  
Nickel Aluminum ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron

AbstractA survey by differential scanning calorimetry (DSC) and recovery during heating of indentations on a series of nickel-aluminum alloys showed that the Ni-36 at.% Al composition has the best potential for a recoverable shape memory effect at temperatures above 100°C. The phase transformations were studied by high temperature transmission electron microscopy (TEM) and by high temperature x-ray diffraction (HTXRD). Quenching from 1200°C resulted in a single phase, fully martensitic structure. The initial quenched-in martensites were found by both TEM and X-ray diffraction to consist of primarily a body centered tetragonal (bct) phase with some body centered orthorhombic (bco) phase present. On the first heating cycle, DSC showed an endothermic peak at 121°C and an exothermic peak at 289°C, and upon cooling a martensite exothermic peak at 115° C. Upon subsequent cycles the 289°C peak disappeared. High temperature X-ray diffraction, with a heating rate of 2°C/min, showed the expected transformation of bct phase to B2 between 100 and 200°C, however the bco phase remained intact. At 400 to 450°C the B2 phase transformed to Ni2Al and Ni5Al3. During TEM heating experiments a dislocation-free martensite transformed reversibly to B2 at temperatures less than 150°C. At higher temperatures (nearly 600°C) 1/3, 1/3, 1/3 reflections from an ω-like phase formed. Upon cooling, the 1/3, 1/3, 1/3 reflections disappeared and a more complicated martensite resulted. Boron additions suppressed intergranular fracture and, as expected, resulted in no ductility improvements. Boron additions and/or hot extrusion encouraged the formation of a superordered bct structure with 1/2, 1/2, 0 reflections.

Influence of Gd Addition on the Structure and Capability of Ni-Mn-In Metamagnetic Shape Memory Alloys

2012 ◽  
Vol 535-537 ◽  
pp. 950-953
Author(s):  
Li Na Bai ◽  
Gui Xing Zheng ◽  
Zhi Jian Duan ◽  
Jian Jun Zhang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Magnetic Properties ◽  
Magnetic Property ◽  
Transition Temperature ◽  
Martensitic Transformation ◽  
Room Temperature ◽  
Vibrating Sample Magnetometry ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

The influences of Gd concentration on martensitic transformation and magnetic properties of NiMnIn alloys were investigated by differential scanning calorimetry (DSC) , vibrating sample magnetometry (VSM), X-ray diffraction (XRD) and etc. It is Observed through the experiment: the addition of Gd enhances martensite transition temperature;X-ray diffraction analysis of experimental alloys is revealed that to the mixture is martensite and austenite at room temperature; content of Gd is not proportional to the improvement of magnetic property.

scholarly journals Martensitic Transformation and Crystalline Structure of Ni50Mn50−xSnx Melt-Spun Heusler Alloys

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 853
Author(s):  
Rim Ameur ◽  
Mahmoud Chemingui ◽  
Tarek Bachaga ◽  
Lluisa Escoda ◽  
Mohamed Khitouni ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Room Temperature ◽  
Solidification Rate ◽  
Heusler Alloys ◽  
X Ray Diffraction ◽  
Key Factors ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Characteristic Temperatures ◽  
Melt Spun

The structure and thermal behavior are key factors that influence the functional response of Ni–Mn–Sn alloys. The present study reports the production as well as the structure and thermal analysis of melt-spun (solidification rate: 40 ms−1) Ni50 Mn50−xSnx (x = 10, 11, 12 and 13 at.%) alloys. X-ray diffraction measurements were performed at room temperature. The austenite state has an L21 structure, whereas the structure of the martensite is 7M or 10M (depending on the Sn/Mn percentage). Furthermore, the structural martensitic transformation was detected by differential scanning calorimetry (DSC). As expected, upon increasing the Sn content, the characteristic temperatures also increase. The same tendency is detected in the thermodynamic parameters (entropy and enthalpy). The e/a control allows the development production of alloys with a transformation close to room temperature.

Investigation on microstructure and martensitic transformation of neodymium-added NiTi shape memory alloys

2016 ◽  
Vol 30 (28) ◽  
pp. 1650286
Author(s):  
Dovchinvanchig Maashaa ◽  
Ulzii-Orshikh Dorj ◽  
Malrey Lee ◽  
Min Hi Lee ◽  
Chunwang Zhao ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
X Ray Diffraction ◽  
Martensitic Transformation Temperature ◽  
Scanning Calorimetry ◽  
Nd Addition ◽  
One Step ◽  
Niti Shape Memory Alloys ◽  
Niti Matrix ◽  
Electronic Microscope

The effect of rare earth element neodymium (Nd) addition on the microstructure and martensitic transformation behavior of Ni[Formula: see text]Ti[Formula: see text]Nd[Formula: see text] ([Formula: see text] = 0, 0.1, 0.3, 0.5 and 0.7 at.%) shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results show that the microstructure of Ni–Ti–Nd ternary alloy consists of NiNd phase, NiTi2 and the NiTi matrix. A one-step martensitic transformation is observed in the alloys. The martensitic transformation temperature Ms increases sharply increasing 0.1–0.7 at.% Nd content is added.

Precipitates Formation in Ti-Ni Equiatomic Alloys due to Annealing Heat Treatment

2010 ◽  
Vol 643 ◽  
pp. 49-54 ◽  
Author(s):  
Carlos Augusto Nascimento Oliveira ◽  
Euclides Apolinário Cabral De Pina ◽  
Cezar Henrique Gonzalez ◽  
Carlos José de Araújo ◽  
U.S.L. Filho ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Martensitic Transformations ◽  
Smart Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metallurgical Investigation ◽  
Annealing Heat Treatment ◽  
Annealing Heat

The use of smart material such as Ti-Ni in actuators application requires an intense mechanical and metallurgical investigation to understand its behavior. This paper studies martensitic transformation using DSC and X-ray diffraction techniques to compare shape memory parameters in Ti-50.2%Ni (A1) and equiatomic Ti-50.0%Ni (A2) Alloys. The as as-received samples were submitted to annealing at 400°C and 500°C for 24 hours then quenched in at 25°C. The influence of heat treatment on martensitic transformations temperatures and the appearance of R-phase were analyzed using DSC and X-ray diffraction.

High-energy synchrotron X-ray diffraction measurements of simple bending of pseudoelastic NiTi shape memory alloy wires

2016 ◽  
Vol 31 (2) ◽  
pp. 104-109 ◽  
Author(s):  
Baozhuo Zhang ◽  
Marcus L. Young
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
High Energy ◽  
Bend Angle ◽  
Niti Shape Memory Alloy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Mechanical Bending ◽  
Xrd Patterns

Many technological applications of austenitic shape memory alloys (SMAs) involve cyclical mechanical loading and unloading in order to take advantage of pseudoelasticity. In this paper, we investigated the effect of mechanical bending of pseudoelastic NiTi SMA wires using high-energy synchrotron radiation X-ray diffraction (SR-XRD). Differential scanning calorimetry was performed to identify the phase transformation temperatures. Scanning electron microscopy images show that micro-cracks in compressive regions of the wire propagate with increasing bend angle, while tensile regions tend not to exhibit crack propagation. SR-XRD patterns were analyzed to study the phase transformation and investigate micromechanical properties. By observing the various diffraction peaks such as the austenite (200) and the martensite (${\bar 1}12$), (${\bar 1}03$), (${\bar 1}11$), and (101) planes, intensities and residual strain values exhibit strong anisotropy, depending upon whether the sample is in compression or tension during bending.

Phase Transformation in Ti-Ni-Ta Shape Memory Alloy

2007 ◽  
Vol 130 ◽  
pp. 147-150 ◽  
Author(s):  
Zdzisław Lekston ◽  
Tomasz Goryczka
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Medical Application ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Martensitic Transformation Temperature ◽  
X Ray ◽  
Solution Treated

A new Ti50Ni48.7Ta1.3 shape memory alloy was designed for medical application. In order to influence the martensitic transformation temperature the alloy was solution treated and additionally aged at 400oC for various time. Phase transformation was studied applying differential scanning calorimeter (DSC) and X-ray diffraction techniques. The ageing causes that the martensitic transformation occurs in two steps: B2↔R↔B19’ during cooling and heating. During cooling the transformations: B2→R and R→B19’ are well separated whereas on heating they are overlapped. Also ageing causes a shift of temperatures of the martensitic transformation into the higher region. It is due to the precipitation process. Precipitates of the Ni4Ti3 phase were observed. Applied thermal treatment leads to shift of the transformation temperatures below temperature of a human body. This makes the Ti-Ni-Ta alloy attractive for application in medicine.

Sign in / Sign up

Export Citation Format

Share Document