The Shape Memory Effect in Melt Spun Fe-15Mn-5Si-9Cr-5Ni Alloys

2013 ◽  
Vol 738-739 ◽  
pp. 247-251 ◽  
Author(s):  
Ana Druker ◽  
Paulo La Roca ◽  
Philippe Vermaut ◽  
Patrick Ochim ◽  
Jorge Malarría
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Melt Spinning ◽  
Room Temperature ◽  
Tensile Tests ◽  
Argon Atmosphere ◽  
Austenitic Phase ◽  
Melt Spun ◽  
Shape Memory Behaviour

At room temperature, Fe-15Mn-5Si-9Cr-5Ni alloys are usually austenitic and the application of a stress induces a reversible martensitic transformation leading to a shape memory effect (SME). However, when a ribbon of this material is obtained by melt-spinning, the rapid solidification stabilizes a high-temperature ferritic phase. The goals of this work were to find the appropriate heat treatment in order to recover the equilibrium austenitic phase, characterize the ribbon form of this material and evaluate its shape memory behaviour. We found that annealing at 1050°C for 60 min, under a protective argon atmosphere, followed by a water quenching stabilizes the austenite to room temperature. The yield stress, measured by tensile tests, is 250 MPa. Shape-memory tests show that a strain recovery of 55% can be obtained, which is enough for certain applications.

Microstructural Features and Shape-Memory Characteristics of Melt-Spun Ni-Al-Fe-B Ribbons

1991 ◽  
Vol 246 ◽  
Author(s):  
C. T. Liu ◽  
C. J. Sparks ◽  
J. A. Horton ◽  
E. P. George ◽  
C. A. Carmichael ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Melt Spinning ◽  
Room Temperature ◽  
Alloy Composition ◽  
X Ray ◽  
Melt Spun ◽  
Bend Angles ◽  
Memory Characteristics

AbstractThis paper summarizes our recent study of NiAI+Fe+B alloy ribbons containing 4 to 20% Fe and doped with 300 wt ppm B. Alloy ribbons were successfully fabricated by rapid solidification via melt spinning. The alloys with 8% Fe and 34% Al-equivalent [=Al%+(Fe%)/2] showed the best bend ductility at room temperature. The ribbons exhibited a reversible martensite (body-centered orthorombic structure) to B2 transformation as evidenced by DSC, X-ray and TEM studies. The shape-memory effect, as characterized by measuring the recovery of bend angles with temperature, is sensitive to alloy composition, with the best recovery observed in SMA-15 (B-doped Ni-27% Al-14% Fe). Annealing at 600°C causes aging embrittlement; in particular, in alloys containing 12% Fe.

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.

scholarly journals Study of Co-Ni-Al Alloys with Magnetically Controlled Shape Memory Effect

2009 ◽  
Vol 635 ◽  
pp. 75-80 ◽  
Author(s):  
Irina I. Kositsyna ◽  
V.A. Zavalishin
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Martensite Transformation ◽  
Melt Spinning ◽  
Al Alloys ◽  
Helium Atmosphere ◽  
Melt Spun ◽  
Transformation Hysteresis ◽  
Start Temperature

The methods of electron microscopy, resistometry and magnetometry are used to study ten (36-38)Co - (32-36)Ni - (27-30)Al (at. %) alloys. Cast coarse-crystalline and microcrystalline alloys made by melt spinning in a helium atmosphere are considered. It is shown that the martensite start temperature Ms becomes 30-50°C lower as grains are refined to 1 m m. Replacement of 1 at. % cobalt by nickel and 1 at. % aluminum by nickel makes the temperature interval of the В2«L10 martensite transformation (30-60)°C and (100-110)°C higher respectively. The martensite transformation hysteresis is about 100 degrees. The melt-spun Co38Ni34Al28 alloy with the transformation temperatures Мs = 31°С, Мf = –34°С, Аs = –6°С, Аf = 70°С and Тс = 98°С is a material possessing the magnetically controlled shape memory effect.

High performance shape memory effect in nitinol wire for actuators with increased operating temperature range

2014 ◽  
Vol 07 (05) ◽  
pp. 1450063 ◽  
Author(s):  
Riccardo Casati ◽  
Carlo Alberto Biffi ◽  
Maurizio Vedani ◽  
Ausonio Tuissi
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
High Performance ◽  
Room Temperature ◽  
Operating Temperature ◽  
Niti Wire ◽  
Shape Memory Actuators ◽  
Nitinol Wire ◽  
Operating Temperature Range

In this research, the high performance shape memory effect (HP-SME) is experimented on a shape memory NiTi wire, with austenite finish temperature higher than room temperature. The HP-SME consists in the thermal cycling of stress induced martensite and it allows achieving mechanical work higher than that produced by conventional shape memory actuators based on the heating/cooling of detwinned martensite. The Nitinol wire was able to recover about 5.5% of deformation under a stress of 600 MPa and to withstand about 5000 cycles before failure. HP-SME path increased the operating temperature of the shape memory actuator wire. Functioning temperatures higher than 100°C was reached.

Cold Bending a Ni-Ti Shape Memory Alloy Wire

2015 ◽  
Vol 661 ◽  
pp. 98-104 ◽  
Author(s):  
Kuang-Jau Fann ◽  
Pao Min Huang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
Aging Treatment ◽  
Treatment Temperature ◽  
Bending Test ◽  
Solution Treatment Temperature

Because of being in possession of shape memory effect and superelasticity, Ni-Ti shape memory alloys have earned more intense gaze on the next generation applications. Conventionally, Ni-Ti shape memory alloys are manufactured by hot forming and constraint aging, which need a capital-intensive investment. To have a cost benefit getting rid of plenty of die sets, this study is aimed to form Ni-Ti shape memory alloys at room temperature and to age them at elevated temperature without any die sets. In this study, starting with solution treatments at various temperatures, which served as annealing process, Ni-rich Ni-Ti shape memory alloy wires were bent by V-shaped punches in different curvatures at room temperature. Subsequently, the wires were aged at different temperatures to have shape memory effect. As a result, springback was found after withdrawing the bending punch and further after the aging treatment as well. A higher solution treatment temperature or a smaller bending radius leads to a smaller springback, while a higher aging treatment temperature made a larger springback. This springback may be compensated by bending the wires in further larger curvatures to keep the shape accuracy as designed. To explore the shape memory effect, a reverse bending test was performed. It shows that all bent wires after aging had a shape recovery rate above 96.3% on average.

Ca2+, redox, and thermoresponsive supramolecular hydrogel with programmed quadruple shape memory effect

2018 ◽  
Vol 54 (58) ◽  
pp. 8084-8087 ◽  
Author(s):  
Linya Tang ◽  
Lanfang Wen ◽  
Shouping Xu ◽  
Pihui Pi ◽  
Xiufang Wen
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Supramolecular Hydrogel ◽  
Redox Responsive ◽  
Regulation Mechanisms ◽  
Shape Memory Behaviour

With a new redox-responsive stimulus coupled with two other common regulation mechanisms, this hydrogel shows programmed quadruple shape memory behaviour.

Effect of Aging on Mechanical Properties of Ti-Mo-Al Biomedical Shape Memory Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2150-2153 ◽  
Author(s):  
Hideki Hosoda ◽  
Makoto Taniguchi ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Shuichi Miyazaki
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Tensile Tests ◽  
Single Step ◽  
Two Phase ◽  
Solution Treated

Effects of single- and multi-step aging on mechanical properties and shape memory properties of Ti-6Mo-8Al (mol%) biomedical shape memory alloy were studied using tensile tests at room temperature (RT). The solution-treated alloy at RT was two phase of bcc β and martensite α". Tensile tests revealed that the solution-treated alloy exhibited good shape memory effect. As for the single-step aging, (1) pseudoelastic shape recovery by unloading was observed after aging at 623K, (2) the alloy became brittle after aging at 773K due to ω embrittlement, and (3) strength was improved with small shape memory effect by aging at 1023K. On the other hand, after a multistep aging at 773K-1023K-1123K, the alloy was strengthened and showed perfect shape recovery. The improvement must be achieved by the formation of fine and uniform hcp α precipitates.

Understanding indentation-induced two-way shape memory effect

2007 ◽  
Vol 22 (10) ◽  
pp. 2851-2855 ◽  
Author(s):  
Yijun Zhang ◽  
Yang-Tse Cheng ◽  
David S. Grummon
Keyword(s):  
Experimental Data ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Contact Radius ◽  
Element Analysis ◽  
Austenitic Phase ◽  
Heating And Cooling ◽  
Surface Protrusion ◽  
Niti Shape Memory Alloys

Spherical indents in NiTi shape memory alloys can have reversible depth change: deeper depth in the martensitic phase at low temperature and shallower depth in the austenitic phase at high temperature. This is the indentation-induced two-way shape memory effect. After polishing the indents, two-way reversible surface protrusions can occur on the shape memory alloy surfaces upon heating and cooling. The height of the surface protrusion is about the same as the depth of the reversible indent. Further polishing reduces the height of the surface protrusion, which disappears completely when the polished depth is about the length of the contact radius. By comparing finite element analysis and experimental data, we show that the depth at which a protrusion disappears is close to the 10% strain boundary. This suggests that slip-plasticity is responsible for the observed indentation-induced two-way shape memory effect.

scholarly journals Design of Ethylene-Vinyl Acetate Copolymer Fiber with Two-Way Shape Memory Effect

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1599 ◽  
Author(s):  
Xiaoming Qi ◽  
Wentong Yang ◽  
Laiming Yu ◽  
Wenjun Wang ◽  
Haohao Lu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Vinyl Acetate ◽  
Memory Effect ◽  
Crosslink Density ◽  
Melt Spinning ◽  
Uv Curing ◽  
Ethylene Vinyl Acetate ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

One-dimensional shape memory polymer fibers (SMPFs) have obvious advantages in mechanical properties, dispersion properties, and weavability. In this work, a method for fabricating semi-crystallization ethylene-vinyl acetate copolymer (EVA) fiber with two-way shape memory effect by melt spinning and ultraviolet (UV) curing was developed. Here, the effect of crosslink density on its performance was systematically analyzed by gel fraction measurement, tensile tests, DSC, and TMA analysis. The results showed that the crosslink density and shape memory properties of EVA fiber could be facilely adjusted by controlling UV curing time. The resulting EVA fiber with cylindrical structure had a diameter of 261.86 ± 13.07 μm, and its mechanical strength and elongation at break were 64.46 MPa and 114.33%, respectively. The critical impact of the crosslink density and applied constant stress on the two-way shape memory effect were analyzed. Moreover, the single EVA fiber could lift more than 143 times its own weight and achieve 9% reversible actuation strain. The reversible actuation capability was significantly enhanced by a simple winding design of the single EVA fiber, which provided great potential applications in smart textiles, flexible actuators, and artificial muscles.

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