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.

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.

Shape Recovery and ε - γ Transformation in Fe29Mn7Si5Cr SMA

2008 ◽  
Vol 59 ◽  
pp. 86-91 ◽  
Author(s):  
Nele Van Caenegem ◽  
Kim Verbeken ◽  
Roumen H. Petrov ◽  
N.M. van der Pers ◽  
Yvan Houbaert
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Recovery ◽  
Electron Backscatter Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Backscatter ◽  
Shape Memory Behaviour ◽  
Backscatter Diffraction

The shape memory behaviour of a Fe29Mn7Si5Cr based alloy has been investigated. Characterization of the martensitic transformation and the different structural constituents was performed using optical microscopy, X-ray diffraction (XRD) methods and electron backscatter diffraction (EBSD). The transformation temperatures and the shape recovery were determined by dilatometry on prestrained samples.

Shape Memory Characteristics of Ti50Ni50-xCux(x=35, 40) Alloy Strips

2008 ◽  
Vol 47-50 ◽  
pp. 463-466
Author(s):  
Yeon Wook Kim ◽  
Tae Hyun Nam ◽  
Sang Hoon Lee
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Alloy Strip ◽  
X Ray Diffraction ◽  
Strip Surface ◽  
X Ray ◽  
Columnar Grains ◽  
One Step ◽  
Transformation Hysteresis ◽  
Memory Characteristics

The shape memory alloy strips of Ti50Ni15Cu35 and Ti50Ni10Cu40 had been fabricated by arc melt overflow. Their microstructures and shape memory characteristics were investigated by means of X-ray diffraction, optical microscopy and differential scanning calorimetries. The microstructure of as-cast strips exhibited columnar grains normal to the strip surface. X-ray diffraction analysis showed that one-step martensitic transformation of B2-B19 occurred in the alloy strips. According to the DSC analysis, it was known that the martensitic transformation temperature (Ms) of B2→B19 was 71.2°C in Ti50Ni15Cu35 and 64.5°C in Ti50Ni10Cu40 alloy strip, respectively. During thermal cyclic deformation with the applied stress of 60 MPa, transformation hysteresis and elongation associated with the B2-B19 transformation were observed to be 4.9°C and 1.4% in Ti50Ni15Cu35 alloy strip. However, Ti50Ni10Cu40 alloy strip was so brittle that its mechanical properties could not be measured.

Comparative Study of Structural and Néel Transition Temperatures in FE-MN-SI Shape-Memory Alloys

1999 ◽  
Vol 604 ◽  
Author(s):  
M.I.N. da Silva ◽  
G.J. de Arruda ◽  
P.E.F. Côrtes ◽  
M.S. Andrade ◽  
R. Paniago ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Mössbauer Spectroscopy ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Mossbauer Spectroscopy ◽  
Magnetic Transition ◽  
Transition Temperatures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ε Martensite

AbstractFe-Mn-Si based alloys exhibit the shape memory effect depending on their composition. Upon cooling, these alloys undergo a martensitic transformation γ (fcc) → ε (hcp), and a magnetic transition, at the Néel temperature, from paramagnetic to antiferromagnetic ordering in the γ-phase. In this work, the structural and magnetic phase transition temperatures were determined in an Fe-27Mn-2.5Si (in weight %) shape-memory alloy, using differential scanning calorimetry, dilatometry, electrical resistivity, Mossbauer spectroscopy, and X-ray diffraction. The transition temperatures measured by the different techniques were almost the same. It was observed, by calorimetry and electrical resistivity measurements, that the magnetic transition temperature upon cooling was very close and slightly higher than that of the start of the martensitic transformation, thus promoting the stabilization of the γ-phase. Consequently, the amount of thermally induced ε-martensite was very small. Mössbauer spectroscopy and X-ray diffraction measurements showed that only 10% of ε-martensite was formed upon cooling to quite low temperatures.

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.

The Stress Relaxation Characteristic and Martensitic Transformation of Fe-Mn-Si Shape Memory Alloys under Different Deformation Condition

2012 ◽  
Vol 430-432 ◽  
pp. 106-109
Author(s):  
Lin Lin Liu ◽  
Cheng Xin Lin ◽  
Chao Yu Zhou
Keyword(s):  
Martensitic Transformation ◽  
Stress Relaxation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Xrd Analysis ◽  
Deformation Condition ◽  
X Ray Diffraction ◽  
X Ray

The stress relaxation characteristic and martensitic transformation in Fe-Mn-Si shape memory alloys under different deformation condition are studied by X-Ray Diffraction (XRD) analysis and TEM observation. The results show that the amount of stress induced ε martensitic quickly increases when the suspending loading time below 10min (0~10min), and the increasing speed of ε martensitic gradually become slower when the suspending loading time above 10min. This is owing to the stabilization of stress induced ε martensitic. The stress relaxation ratio of Fe-17Mn-5Si-10Cr-5Ni and Fe-17Mn-5Si-2Cr-2Ni-1V alloys increase with increasing the suspending loading time, and the relaxation ratio of Fe-17Mn-5Si-2Cr-2Ni-1V alloy is obviously lower than that of Fe-17Mn-5Si-10Cr-5Ni alloy.

The Constrained Stress-Induced ε Reverse Martensitic Transformation Characteristic of Fe-Mn-Si Alloy Embedded in Cement Matrix

2010 ◽  
Vol 44-47 ◽  
pp. 2229-2233 ◽  
Author(s):  
Lin Lin Liu ◽  
Cheng Xin Lin ◽  
Chao Yu Zhou
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Reverse Transformation ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
Temperature Zone ◽  
Alloy Wire ◽  
Reverse Martensitic Transformation ◽  
X Ray

The constrained stress-induced ε reverse martensitic transformation characteristic of Fe-17Mn-5Si-10Cr-5Ni shape memory alloy wire embedded in cement matrix was studied by X-Ray Diffraction (XRD) and metallographical. The results show that the finish temperature (Af) of the constrained reverse transformation of Fe-17Mn-5Si-10Cr-5Ni shape memory alloy in cement matrix, compared with the unconstrained alloy, is elevated. With increasing the pre-strain, the Af is higher, and reverse transformation temperature zone is broadened. The main result which causes martensitic reverse transformation harder is that Fe-Mn-Si alloy deformation coordination is limited by cement matrix constrained.

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