The shape memory mechanism associated with the martensitic transformation in TiNi alloys—II. Variant coalescence and shape recovery

1989 ◽  
Vol 37 (7) ◽  
pp. 1885-1890 ◽  
Author(s):  
S. Miyazaki ◽  
K. Otsuka ◽  
C.M. Wayman
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Recovery ◽  
Memory Mechanism ◽  
Ni Alloys

Shape Memory Effect in Co-Ni Polycrystalline Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 2029-2032 ◽  
Author(s):  
Wei Min Zhou ◽  
Yan Liu ◽  
Bohong Jiang ◽  
Xuan Qi
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Recoverable Strain ◽  
Ni Alloys ◽  
Ni Content ◽  
Polycrystalline Alloys ◽  
Ni Alloy

Co-Ni alloys exhibit g(fcc)®e(hcp) martensitic transformation and show reversible induced strain under applied magnetic field, which means they are potential magneto-shape-memory materials. Polystalline of Co-Ni alloys with varied Ni content were prepared. The g(fcc)®e(hcp) martensitic transformation and shape memory effect (SME) of Co-Ni alloy were studied. The influences of Ni content and deformation temperature on SME were discussed. The shape recovery rate and recoverable strain decrease with the increase of Ni content.

scholarly journals Shape-Memory-Recovery Characteristics of Microcellular Foamed Thermoplastic Polyurethane

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 351
Author(s):  
Chang-Seok Yun ◽  
Joo Seong Sohn ◽  
Sung Woon Cha
Keyword(s):  
Shape Memory ◽  
Cell Density ◽  
Shape Recovery ◽  
Structural Changes ◽  
Thermoplastic Polyurethane ◽  
Testing Machine ◽  
Base Material ◽  
Memory Mechanism ◽  
Foaming Process ◽  
Dog Bone

We investigated the shape-recovery characteristics of thermoplastic polyurethane (TPU) with a microcellular foaming process (MCP). Additionally, we investigated the correlation between changes in the microstructure and the shape-recovery characteristics of the polymers. TPU was selected as the base material, and the shape-recovery characteristics were confirmed using a universal testing machine, by manufacturing dog-bone-type injection-molded specimens. TPUs are reticular polymers with both soft and hard segments. In this study, we investigated the shape-memory mechanism of foamed polymers by maximizing the shape-memory properties of these polymers through a physical foaming process. Toward this end, TPU specimens were prepared by varying the gas pressure, foaming temperature, and type of foaming gas in the batch MCP. The effects of internal structural changes were investigated. These experimental variables affected the microstructure and shape-recovery characteristics of the foamed polymer. The generated cell density changed, which affected the shape-recovery characteristics. In general, a higher cell density corresponded to a higher shape-recovery ratio.

scholarly journals Nanoscale Mechanical Properties of Nanoindented Ni48.8Mn27.2Ga24 Ferromagnetic Shape Memory Thin Film

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
Xiaofei Fu ◽  
Chao Liu ◽  
Xili Lu ◽  
Xianli Li ◽  
Jingwei Lv ◽  
...  
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Martensitic Transformation ◽  
Magnetron Sputtering ◽  
Shape Memory ◽  
Room Temperature ◽  
Shape Recovery ◽  
Recovery Ratio ◽  
Dc Magnetron Sputtering ◽  
Ferromagnetic Shape Memory

The structure and nanoscale mechanical properties of Ni48.8Mn27.2Ga24 thin film fabricated by DC magnetron sputtering are investigated systematically. The thin film has the austenite state at room temperature with the L21 Hesuler structure. During nanoindentation, stress-induced martensitic transformation occurs on the nanoscale for the film annealed at 823 K for 1 hour and the shape recovery ratio is up to 85.3%. The associated mechanism is discussed.

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.

scholarly journals Nanoscale twinning in Fe–Mn–Al–Ni martensite: a backscatter Kikuchi diffraction study

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Peter D. B. Fischer ◽  
Stefan Martin ◽  
Alexander Walnsch ◽  
Martin Thümmler ◽  
Mario J. Kriegel ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Diffraction Study ◽  
Face Centered Cubic ◽  
Ni Alloys ◽  
Heat Treated ◽  
Iron Based ◽  
Face Centered ◽  
Ice Water ◽  
Interstitial Elements

Iron-based Fe–Mn–Al–Ni shape-memory alloys are of rather low materials cost and show remarkable pseudoelastic properties. To further understand the martensitic transformation giving rise to the pseudoelastic properties, different Fe–Mn–Al–Ni alloys have been heat treated at 1473 K and quenched in ice water. The martensite, which is formed from a body-centred cubic austenite, is commonly described as face-centered cubic (f.c.c.), even though there are also more complex, polytypical descriptions of martensite. The presently studied backscatter Kikuchi diffraction (BKD) patterns have been evaluated, showing a structure more complex than simple f.c.c. This structure can be described by nanoscale twins, diffracting simultaneously in the exciting volume. The twinned structure shows a tetragonal distortion, not uncommon for martensite in spite of the lack of interstitial elements. These features are evaluated by comparing the measured BKD patterns with dynamically simulated ones.

Influence of the Particle Size on Phase Transformation Temperatures of Ni-49at.%Ti Shape Memory Alloy Powders

2010 ◽  
Vol 660-661 ◽  
pp. 124-127
Author(s):  
George Carlos S. Anselmo ◽  
Walman Benício de Castro ◽  
Carlos José de Araújo
Keyword(s):  
Particle Size ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Particle Sizes ◽  
Gas Atomization ◽  
Scanning Calorimetry ◽  
Transformation Temperatures ◽  
Ni Alloys ◽  
Material Saving ◽  
Start Temperature

It is important to control the martensitic transformation start temperature (Ms) of Ti–Ni alloys because it determines the temperature range over which the shape memory effect and superelasticity appear. Powder metallurgy (PM) is known to provide the possibility of material-saving and automated fabrication of at least semi-finished products as well as net-shape components for NiTi alloys. In this study powder with different particle sizes was subjected by gas atomization. The evolution of the control the martensitic transformation start temperature (Ms) was studied by differential scanning calorimetry. The effect of the particle size of powders on the transformation temperatures behaviors was discussed.

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