Temperature memory effect of martensite and R-phase transformation in TiNi-based shape memory alloys

2007 ◽  
Author(s):  
H. J. Yu ◽  
Z. G. Wang ◽  
X. T. Zu ◽  
Y. Q. Fu
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Memory Effect ◽  
Temperature Memory Effect

Suppression of Martensitic Phase Transformation, Shape Memory and High Damping by Ion Implantation in Ni-Ti Thin Films

2006 ◽  
Vol 319 ◽  
pp. 17-24
Author(s):  
Rolf Gotthardt
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Memory Effect ◽  
Ion Irradiation ◽  
Amorphous State ◽  
Amorphous Layer ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Damping Capacity

The shape memory effect and the high damping in shape memory alloys are based on the martensitic phase transformation, which takes place essentially without diffusion and any change of order have an influence on its side effects: the memory effect, the superelasticity and the high damping capacity of the martensitic phase. A new method to control the performance of shape memory alloys is presented, which is based on selective modification of specified parts of working components. In this research, ion irradiation has been used to introduce locally disorder into a crystal or even amorphise it. A pre-deformed Ni-Ti, 6μm thin film in its martensitic state has been irradiated with Ni-ions of energy of 5 MeV up to a dose of 1016 ions/cm2. By this treatment, a 2μm thin surface layer has been finally transformed into an amorphous state, in which the martensitic transformation is suppressed. During heating the underlying non-modified layer is contracting and an out-of-plane movement is observed. The amorphous layer is elastically deformed and its energy is used during cooling to bring the film in its original shape. In this way, a reversible movement of the film is created. This new technique not only allows us to design new types of micro-actuators, but also to influence locally the high damping, which can be of great importance for micro-engineering applications.

Temperature memory effect in Cu–Al–Ni shape memory alloys studied by adiabatic calorimetry

2008 ◽  
Vol 56 (15) ◽  
pp. 3711-3722 ◽  
Author(s):  
Javier Rodríguez-Aseguinolaza ◽  
Isabel Ruiz-Larrea ◽  
Maria Luisa Nó ◽  
Angel López-Echarri ◽  
José María San Juan
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Memory Effect ◽  
Adiabatic Calorimetry ◽  
Temperature Memory Effect

Temperature memory effect in CuAlNi single crystalline and CuZnAl polycrystalline shape memory alloys

2006 ◽  
Vol 448 (1) ◽  
pp. 69-72 ◽  
Author(s):  
Z.G. Wang ◽  
X.T. Zu ◽  
H.J. Yu ◽  
X. He ◽  
C. Peng ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Memory Effect ◽  
Single Crystalline ◽  
Temperature Memory Effect

Numerical simulation of the behavior of steel T-stubs connected by Fe-based shape memory alloy bolts

2018 ◽  
Vol 29 (16) ◽  
pp. 3284-3292 ◽  
Author(s):  
Cheikh Cissé ◽  
Wael Zaki ◽  
Tarak Ben Zineb
Keyword(s):  
Numerical Simulation ◽  
Plastic Deformation ◽  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Implicit Time ◽  
Integration Scheme ◽  
Iron Based

The article focuses on the numerical simulation of the thermomechanical behavior of steel T-stubs connected by iron-based shape memory alloys bolts. The three-dimensional macroscopic model used in this work was previously developed by the authors considering different thermomechanical properties between austenite and martensite, and coupling between phase transformation and plasticity. The model is implemented in a UMAT code using an implicit time-discrete integration scheme that follows a “multisurface plasticity”-like approach. The numerical results show that the shape memory effect can be used to preload the bolt if the initial length of its shank is less than the total thickness of the flanges. For an initial shank length of 21.38 mm and a total flange thickness of 21.4 mm, the shape memory effect produced average contact forces of 101 N between the bolt head and the flange, and 37 N between the two flanges. The resulting average contact pressures were 210 and 25 MPa, respectively. The average bolt force after preload was approximately 22.6 kN. Subsequent application of 2 mm normal displacements at the top and bottom faces of the upper and lower webs induced local plastic deformation around the flange holes and phase transformation in the bolt. The reversibility of martensitic transformation and the confinement of the plastic deformation in a limited zone around the holes allowed nearly complete shape recovery by heating. The obtained results highlight the advantage of using low-cost iron-based shape memory alloys as alternatives to steel bolts for connecting T-stubs.

Shape Memory Alloys

MRS Bulletin ◽  
1993 ◽  
Vol 18 (4) ◽  
pp. 49-56 ◽  
Author(s):  
C.M. Wayman
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Parent Phase ◽  
Martensite Phase ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Lower Temperature

Numerous metallic alloys are now known to exhibit a shape memory effect through which an article deformed at a lower temperature will regain its original undeformed shape when heated to a higher temperature. This behavior is basically a consequence of a martensitic phase transformation. When compared, the various shape memory materials are found to have common characteristics such as atomic ordering, a thermoelastic martensitic transformation that is crystallographically reversible, and a martensite phase that forms in a self-accommodating manner. The explanation of the shape memory phenomenon is now universal and well in hand. In addition to the familiar “one-way” memory, shape memory alloys also exhibit a “two-way” memory as well and a “mechanical” shape memory resulting from the formation and reversal of stressinduced martensite.Fundamental to the shape memory effect (SME) is the occurrence of a martensitic phase transformation and its subsequent reversal Basically, a shape memory alloy (SMA) is deformed in the martensitic condition (martensite), and the shape recovery occurs during heating when the specimen undergoes a reverse transformation of the martensite to its parent phase. This is the essence of the shape memory effect. Materials that exhibit shape memory behavior also show a two-way shape memory, as well as a phenomenon called superelasticity. These are also discussed.The shape memory response after deformation and thermal stimulation constitutes “smart” behavior, i.e., Stimulated Martensite-Austenite Reverse Transformation.

Repeatable temperature memory effect of TiNi shape memory alloys

2009 ◽  
Vol 63 (11) ◽  
pp. 949-951 ◽  
Author(s):  
Yanjun Zheng ◽  
Juntao Li ◽  
Lishan Cui
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Memory Effect ◽  
Temperature Memory Effect
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