Magnetization and shape memory effect of ferromagnetic shape memory alloy wire

1999 ◽  
Vol 35 (5) ◽  
pp. 3403-3405 ◽  
Author(s):  
T. Kanada ◽  
M. Enokizono
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Memory Alloy Wire ◽  
Ferromagnetic Shape Memory Alloy ◽  
Alloy Wire ◽  
Ferromagnetic Shape Memory

Hot Forming a V-Shaped Ni-Ti Shape Memory Alloy Wire

2014 ◽  
Vol 626 ◽  
pp. 377-382
Author(s):  
Kuang-Jau Fann ◽  
Hau Chi Hsu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
Phase State ◽  
Process Temperature ◽  
Shape Memory Alloy Wire ◽  
Austenitic Phase ◽  
Alloy Wire

Ni-Ti shape memory alloys have shape memory effect, that if they are deformed from martensitic phase state at a lower temperature, they will recover their original shape by heating them to austenitic phase state. To have them for an application using this shape memory effect, usually they undergo a constraint aging after plastic deformation. That is, they are fixed with tool set and together heat treated in a furnace after they are formed at room temperature. However a large load is needed to form them at room temperature. Thus, this study is aimed to lower the forming load by combining the forming and aging process together in a furnace at high temperature. In this study, a Ni-Ti shape memory alloy wire having a diameter of 0.63 mm is bent in a heated chamber at 450°C, 500°C, 550°C, and 600°C, respectively, by a V-shaped punch of 2 mm in radius to an angle of 60°, then held along with the die set at its dead center in the chamber for maximum one hour long, and then quenched in the water. All of the bent wires have the shape memory effect. That is, the wires recover their bent geometry once they are unbent at about 4°C and heated again at about 100°C. The experiment results showed that the bent wires can have the geometry accuracy as desired because of stress relaxation found in the process, which depends on the process temperature and duration. As a result, the higher the process temperature is and the longer the duration is, the better the accuracy of the formed wires is.

Thermomechanical Forming of NiTi Shape Memory Alloy Wire

2014 ◽  
Vol 939 ◽  
pp. 430-436 ◽  
Author(s):  
Kuang Jau Fann ◽  
Hau Chi Hsu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Niti Shape Memory Alloy ◽  
Processing Temperature ◽  
Shape Memory Alloy Wire ◽  
Alloy Wire ◽  
Niti Shape Memory Alloys

Because of their smart characteristics with shape memory effect and superelasticity, NiTi shape memory alloys used in sensors and actuators are regarded as an emerging applied material with high added value by their additional biomedical compatibility for medical devices and implants. It is meaningful to pay more attention to study the production technique of NiTi shape memory alloys. For this reason, this article is aimed to investigate the results of a NiTi shape memory alloy wire in thermomechanical forming process regarding the processing temperature and duration. Thereafter a NiTi shape memory alloy wire of 0.63 mm in diameter is formed in a furnace at 450°C, 500°C, 550°C, and 600°C, respectively, by a semi cylindrical punch of 32 mm in diameter, then held together with the die set in the furnace for 10, 30, and 50 minutes long, respectively, and then quenched in the water. All of the formed wires have shape memory effect. That is, the wires returned their formed geometry once they were straightened below martensite transformation finishing temperature about room temperature and heated again above austenite transformation finishing temperature about 70°C. These thermomechanical forming processes were also investigated by commercial finite element software DEFORM. Both analytical and experimental results showed that the formed wires could not have the geometry precision as wanted because of stress relaxation found in process, which depends on the process temperature and the treatment duration. As a result, the lower the temperature and the shorter the duration is, the larger the springback is. That means that the higher the treatment temperature is and the longer the holding time is, the better the precision of the formed part is.

Transformation hysteresis and shape memory effect of an ultrafine-grained TiNiNb shape memory alloy

2014 ◽  
Vol 54 ◽  
pp. 133-135 ◽  
Author(s):  
P.C. Jiang ◽  
Y.F. Zheng ◽  
Y.X. Tong ◽  
F. Chen ◽  
B. Tian ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Ultrafine Grained ◽  
Transformation Hysteresis
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