Structure and mobility of martensite variant interfaces in a Cu-Zn-AI shape memory alloy

2003 ◽  
Vol 112 ◽  
pp. 519-522 ◽  
Author(s):  
W. Cai ◽  
J. X. Zhang ◽  
Y. F. Zheng ◽  
L. C. Zhao
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Martensite Variant

Incompatibility of Martensite Variant Clusters in Self-accommodation Microstructure in Ti-Ni-Pd High Temperature Shape Memory Alloy

2015 ◽  
Vol 1760 ◽  
Author(s):  
Takeshi Teramoto ◽  
Masaki Tahara ◽  
Hideki Hosoda ◽  
Tomonari Inamura
Keyword(s):  
High Temperature ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Habit Plane ◽  
Nonlinear Theory ◽  
Geometrically Nonlinear ◽  
Martensite Variant ◽  
Geometrically Nonlinear Theory ◽  
Electron Backscattering Diffraction ◽  
Diamond Cluster

ABSTRACTThe formation frequency of habit plane variant (HPV) clusters in Ni-25Pd-50Ti shape memory alloy was analyzed using electron backscattering diffraction (EBSD) on the basis of the geometrically nonlinear theory of martensite. Two types of cluster, diamond and wedge, were most commonly observed. The ratio of the formation frequency of the diamond to wedge clusters was approximately 1 : 3, whereas the rotation to keep the kinematic compatibility (KC) condition, θ *, was 3.9° and 0.0032°, respectively. The ratio of the formation frequency is quantified by the value of θ * which is an indicator of the incompatibility of the cluster. The origin of the diamond cluster is discussed based on the degree of incompatibility.

Heating and Loading Paths to Optimize the Performance of Trained Shape Memory Alloy Torsional Actuators

2016 ◽  
Author(s):  
Douglas E. Nicholson ◽  
Micheal A. Bass ◽  
James H. Mabe ◽  
Othmane Benafan ◽  
Santo A. Padula ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
Martensite Variant ◽  
Load Paths ◽  
Martensitic State ◽  
The Stability ◽  
In Situ Neutron Diffraction

Near-equiatomic NiTi shape memory alloy (SMA) torsional tube actuators were trained for two-way shape memory effect (TWSME) by repeated thermal cycling under an isobaric load. Performance of the trained actuators was assessed by thermally cycling through a complete phase transformation under a range of isobaric loads that varied from negative to positive and included loads near zero. To assess the actuation performance of the trained SMA components, extended isobaric thermal cycling and cycling under varying loads to constant strain limits was performed. Additionally, isothermal loading was applied in the fully martensitic state prior to and following training. Results show stable TWSME when cycling under significant isobaric loading in the trained direction, however at low or negative loads (loads applied opposite to the training direction) a degradation of TWSME occurred during thermal cycling. Isothermal loading showed that martensite variant reorientation and detwinning was redistributed in the trained actuator when compared to an untrained actuator. Thermal cycling against constant strain limits was shown to have a negligible effect on the stability of the TWSME and overall performance of the trained actuator. Various combinations of isothermal and isobaric loading were shown to expand the operating range at low and negative loads. Additionally, load paths were identified which limit the degradation of TWSME over extended cycling. The aforementioned results are discussed in the context of the correlation between uniaxial isobaric and isothermal loading and texture measurements obtained by in-situ neutron diffraction at stress and temperature. These results show various thermomechanical combinations of heating and loading sequences that yield the same final martensite texture in SMA, which highlights the ability to take different paths yet still obtain the desired actuator response while minimizing irrecoverable deformation mechanisms. The implications of extending these uniaxial results to the design and fabrication and ultimately improving the performance of torsional SMA actuators are discussed.

Compression Behavior and Texture Development of Polymer Matrix Composites Based on NiMnGa Ferromagnetic Shape Memory Alloy Particles

2010 ◽  
Vol 654-656 ◽  
pp. 2103-2106 ◽  
Author(s):  
Motoki Okuno ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Hideki Hosoda
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Young’S Modulus ◽  
Polymer Matrix Composites ◽  
Young's Modulus ◽  
Texture Development ◽  
Compression Tests ◽  
Ferromagnetic Shape Memory Alloy ◽  
Martensite Variant ◽  
Ferromagnetic Shape Memory

Deformation behavior and texture development of NiMnGa ferromagnetic shape memory alloy (FSMA) particles embedded polymer composites were investigated by compression tests and X-ray diffraction pole-figure analysis (XRD-PF). Both the NiMnGa/silicone and NiMnGa/epoxy composites exhibited a characteristic three-stage deformation which is often seen in shape memory alloys due to martensite variant reorientation. XRD-PF revealed that (004) texture was developed in the compressed NiMnGa/silicone due to the retention of martensite variant reorientation. On the other hand, significant texture change was not recognized in the compressed NiMnGa/epoxy. Rearranged martensite variants was kept after unloading in silicone matrix having low Young's modulus, but reverse reorientation occurred in epoxy matrix with high Young's modulus. The rearrangement behavior of martensite variants is strongly affected by elastic properties of matrix.

Energy harvesting using martensite variant reorientation mechanism in a NiMnGa magnetic shape memory alloy

2007 ◽  
Vol 90 (17) ◽  
pp. 172505 ◽  
Author(s):  
I. Karaman ◽  
B. Basaran ◽  
H. E. Karaca ◽  
A. I. Karsilayan ◽  
Y. I. Chumlyakov
Keyword(s):  
Energy Harvesting ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Magnetic Shape Memory ◽  
Martensite Variant ◽  
Magnetic Shape Memory Alloy
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