Shape Memory Effect Improvement and Study of the Corrosion Resistance of the Fe-8Mn-6Si-13Cr-6Ni-12Co Alloy

2012 ◽  
Vol 476-478 ◽  
pp. 2162-2170 ◽  
Author(s):  
Amine Charfi ◽  
Fehmi Gamaoun ◽  
Tarak Bouraoui ◽  
Chedly Bradai ◽  
Bernard Normand
Keyword(s):  
Corrosion Resistance ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
316L Stainless Steel ◽  
Experimental Tests ◽  
Good Corrosion Resistance ◽  
Resistance Tests ◽  
Better Than

Fe-8Mn-6Si-13Cr-6Ni-12Co shape memory alloys are characterized by a good corrosion resistance and a modest shape memory effect. Experimental tests of the corrosion resistance of Fe-8Mn-6Si-13Cr-6Ni-12Co have been studied and compared with the Fe-32Mn-6Si alloy using weight loss, free corrosion and polarization resistance tests. The shape memory effect measurement of the Fe-8Mn-6Si-13Cr-6Ni-12Co and Fe-32Mn-6Si alloys has been also tested after 5% of deformation. The results of corrosion experimental tests show that the Fe-8Mn-6Si-13Cr-6Ni-12Co SMA is not very active in the Na2SO4 solution at pH4 at room temperature. In addition, its corrosion resistance is better than the Fe-32Mn-6Si and almost similar to the 316L stainless steel. To improve the shape memory effect of the Fe-8Mn-6Si-13Cr-6Ni-12Co, a thermomechanical treatment has been applied by 8% prestrain in tensile and followed by heat treatment at 1320K for 1 hour. The results show an improvement in the shape memory effect after 5% of deformation in tensile test.

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.

Phase Constitution, Mechanical Property and Corrosion Resistance of the Ti-Nb Alloys

2006 ◽  
Vol 324-325 ◽  
pp. 655-658 ◽  
Author(s):  
Bao Lai Wang ◽  
Yan Bo Wang ◽  
Yu Feng Zheng
Keyword(s):  
Corrosion Resistance ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Artificial Saliva ◽  
X Ray Diffraction ◽  
Phase Constitution ◽  
Β Phase ◽  
Bending Strain ◽  
35Nb Alloy

Recently, people devote to the development of Ni-free shape memory alloys in order to avoid the Ni-hypersensitivity and toxicity and pursue absolute safety. The shape memory effect and superelasticity have been reported in the biomedical Ti-Nb based alloys. The purpose of this paper is to report the phase constitution, tensile property, shape memory effect and corrosion resistance of the Ti-Nb alloys. The phase constitutions of the Ti-Nb alloys are investigated by means of X-ray diffraction (XRD). The results reveal that β+α′′ phases are presented in the Ti-35Nb alloy and only β phase in the Ti-52Nb alloy at room temperature. The tensile test and bending tests indicate that the Ti-35Nb alloy exhibits shape memory effect. The shape recovery ratio is near to 80% when the bending strain is 4.4% and decreases with the increase of the total bending strain. The corrosion resistance of the Ti-Nb alloys in the Hank's solution and artificial saliva (pH=7.4) at 37 are investigated by OCP, Tafel and anodic polarization methods. The results indicate that the Ti-35Nb alloy has a better corrosion resistance in the artificial saliva and can replace the Ti-Ni alloy in the dental application. In the non-oral condition, the Ti-52Nb alloy may be preferable.

A Study on the Corrosion Resistance and Shape-Memory Effect of FeMnSiCrNiCo Shape-Memory Alloy

2002 ◽  
Vol 394-395 ◽  
pp. 435-438 ◽  
Author(s):  
Zhi Zhong Dong ◽  
Wen Xi Liu ◽  
Defa Wang ◽  
Jin Ming Chen ◽  
Dao Zhi Liu
Keyword(s):  
Corrosion Resistance ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect

Self-Post-Tensioning for Concrete Beams Using Shape Memory Alloys

2014 ◽  
Author(s):  
Muhammad Sherif ◽  
Osman Ozbulut ◽  
Asheesh Landa ◽  
Reginald F. Hamilton
Keyword(s):  
Corrosion Resistance ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Concrete Beams ◽  
Heat Of Hydration ◽  
Image Correlation ◽  
Temperature Hysteresis ◽  
Post Tensioning

This study explores the use of shape memory alloys for self-post-tensioning concrete beams. SMAs have the ability to regain their original shape after being deformed up to 6–8% strain. This shape recovery is a result of an underlying reversible solid-solid phase transformation, which can be induced by either a stress (superelastic effect) or a temperature change (shape memory effect). The shape memory effect can be exploited to prestress concrete. The heat of hydration of grout can thermally activate SMA tendons to obtain self-post-tensioned (SPT) concrete. NiTi-based SMAs are promising due to their corrosion resistance and resistance against low frequency/cycle fatigue failure. NiTiNb alloys are a class of SMAs that exhibit a wide temperature hysteresis and transformation temperatures near the service temperatures required for practical application. Here, NiTiNb shape memory alloys are studied to design an optimized SMA that can be activated using hydration heat. The material design and characterization of the SMA tendons are discussed. The temperature increase due to the heat of hydration of four commercially available grouts is investigated. The bond behavior of SMA tendons is evaluated through pullout tests. Digital Image Correlation method is used for monitoring the slippage of the SMA tendons. The feasibility of developing SPT concrete is assessed through experimental studies. The use of SMAs, which possess high fatigue and corrosion resistance, as post-tensioning tendons in concrete members will increase the service life and provide life cycle cost savings for concrete bridges. The replacement of steel tendons with SMA prestressing tendons will prevent corrosion-induced deterioration of tendons in concrete structures. The use of heat of hydration of grout to activate the shape memory effect of SMA tendons will provide self-stressing capability. This will greatly simplify the tendon installation. The need for jacking equipment or electrical source will be eliminated.

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.

Towards Novel Light-Activated Shape Memory Polymer: Thermomechanical Properties of Photo-responsive Polymers

2005 ◽  
Vol 872 ◽  
Author(s):  
Emily A. Snyder ◽  
Tat H. Tong
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
Shape Memory Polymer ◽  
Crosslinking Density ◽  
Material System ◽  
Effect Change ◽  
Responsive Polymers ◽  
Original Shape

AbstractThe basic principle for the operation of a thermally stimulated shape memory polymer (SMP) is a drastic change in elastic modulus above the glass transition temperature (Tg). This change from glassy modulus to rubbery modulus allows the material to be deformed above the Tg and retain the deformed shape when cooled below the Tg. The material will recover its original shape when heated above the Tg again. However, thermal activation is not the only possibility for a polymer to exhibit this shape memory effect or change of modulus. This paper discusses results of an alternative approach to SMP activation.It is well known that the Tg of a thermosetting polymer is proportional to its crosslinking density. It is possible for the crosslinking density of a room temperature elastomer to be modified through photo-crosslinking special photo-reactive monomer groups incorporated into the material system in order to increase its Tg. Correspondingly, the modulus will be increased from the rubbery state to the glassy state. As a result, the material is transformed from an elastomer to a rigid glassy photoset, depending on the crosslinking density achieved during exposure to the proper wavelength of light. This crosslinking process is reversible by irradiation with a different wavelength, thus making it possible to produce light-activated SMP materials that could be deformed at room temperature, held in deformed shape by photo-irradiation using one wavelength, and recovered to the original shape by irradiation with a different wavelength.In this work, monomers which contain photo-crosslinkable groups in addition to the primary polymerizable groups were synthesized. These monomers were formulated and cured with other monomers to form photo-responsive polymers. The mechanical properties of these materials, the kinetics, and the reversibility of the photo-activated shape memory effect were studied to demonstrate the effectiveness of using photo-irradiation to effect change in modulus (and thus shape memory effect).

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