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Saturday, 5 June 2010

Metallurgy-Materials Science pick of the month by french popular science magazine La Recherche brings SMA-Shape Memory Alloys to the fore

In fact two SMA article summaries are reported in this post

Ferrous Polycrystalline Shape-Memory Alloy Showing Huge Superelasticity by
Y. Tanaka,1 Y. Himuro,1 R. Kainuma,2,* Y. Sutou,1 T. Omori,1 K. Ishida1, published in Science from the American Association for the Advancement of Science AAAS.

Shape-memory alloys, such as Ni-Ti and Cu-Zn-Al, show a large reversible strain of more than several percent due to superelasticity. In particular, the Ni-Ti–based alloy, which exhibits some ductility and excellent superelastic strain, is the only superelastic material available for practical applications at present. We herein describe a ferrous polycrystalline, high-strength, shape-memory alloy exhibiting a superelastic strain of more than 13%, with a tensile strength above 1 gigapascal, which is almost twice the maximum superelastic strain obtained in the Ni-Ti alloys. Furthermore, this ferrous alloy has a very large damping capacity and exhibits a large reversible change in magnetization during loading and unloading. This ferrous shape-memory alloy has great potential as a high-damping and sensor material.

1 Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan.
2 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8579, Japan.

What Others Say
Physics Today Blog
http://blogs.physicstoday.org/update/2010/03/

Un alliage très élastique et pas cher/ A very elastic inexpensive alloy
http://www.larecherche.fr/content/actualite-matiere/article?id=27546

Science Editor recommends a 2nd paper on SMAs recommends also

Materials Science:
Expanding the Repertoire of Shape Memory Alloys
Ji Ma and Ibrahim Karaman
The exceptional properties of many materials often come at the expense of limited performance in other areas. For example, conventional metals and their alloys are strong—they are good at resisting stress (i.e., an applied load)—but they tolerate only a very small amount of strain (i.e., deformation) before they are irreversibly deformed. Rubber can easily return to its original shape, even after large deformations, but is much weaker than conventional metals. However, some metal alloys exhibit "shape memory"; they are strong but can recover from being deformed when heated. This process seems counter-intuitive, but these alloys take advantage of solid-to-solid "diffusionless" phase transitions: The atoms rearrange how they pack into crystals in an orderly fashion, and this process changes the material's macroscopic shape. Few other materials possess this combination of strength and flexibility (see the figure), and clever engineering has exploited these properties—for example, in implanted medical devices such as stents. On page 1488 of this issue, Tanaka et al. (1) report on a superelastic alloy that almost doubles the useful range of deformation that can be induced in such alloys.

Materials Science and Engineering Interdisciplinary Program and Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA.
en référence à : Expanding the Repertoire of Shape Memory Alloys -- Ma and Karaman 327 (5972): 1468 -- Science (afficher sur Google Sidewiki)

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Metaklett-steel grips, Biomimicry and Shape Memory Alloy meanders



Footnote: 1 News dates from March 2010 but published in La Recherche's June Issue.
                2. Nitol is used as an example . The current SMA reported above is reportedly better and cheaper. The alloys appear on first sight very much cheaper than the books (2$/22gm) cf details of Nitol product offer on AMAZON below





Footnote: 1 News dates from March 2010 but published in La Recherche's June Issue.
             


















  2. Nitol is used as an example . The current SMA reported above is reportedly better and cheaper. The alloys appear on first sight very much cheaper than the books (2$/22gm) cf details of Nitol product offer on AMAZON below
Nitol Product Features:
ASTM F2063, Straight, Annealed Temper, Super Elastic Alloy, May be Strained 8-10 times More Than Spring Steel, Superior Corrosion Resistance
Product Details cf advert.

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High Purity Cr sources for Superalloys

Energy for th Future:Phil.Trans.A-Vol. 365, N° 1853 / April 15, 2007, curtesy The Royal Soc. London

Engineered foams and porous materials: Phil Trans A. Vol 364, N° 1838 / 06 curtesy_The R Soc. Lond