New shape-shifting metals discovered

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A new shape-changing metal crystal is reported in the journal Nature, by scientists at University of Minnesota.

It is the prototype of a new family of smart materials that could be used in applications ranging from space vehicles to electronics to jet engines.

Called a "martensite", the crystal has two different arrangements of atoms, switching seamlessly between them.

It can change shape tens of thousands of times when heated and cooled without degrading, unlike existing technology.

Currently, martensite metals are made of an alloyed mixture of nickel and titanium.

They have the remarkable ability to "remember" their shape and even after being bent will return to their original form. For this, they are called "shape memory" metals.

Written By: Simon Redfern
continue to source article at bbc.co.uk

5 COMMENTS

    • In reply to #1 by Roedy:

      I once had some nitinol glasses temples. I presume there were shaped by heating then bending into shape. How do you shape these 2-state memory alloys?

      You heat them up past a specified temperature and hold them in position while they cool. Then you can easily bend them below another specified temp. Between those two temperatures, the material goes “superelastic.” (see link) I know a researcher who has made bars of single crystal SMA that bend just like rubber, but are solid metal.

  1. The name “nitinol” is a sort of acronym that harks back to the alloy’s development:

    NIckel TItanium Naval Ordnance Laboratory.

    I use instruments made of NiTi for root canal procedures. These have revolutionized the field of endodontics in the last 20 years, and there are new developments all the time. :-)

    Steve

  2. Hear that?? Clanging of the rusty old bell of memory, from 40 yrs ago when I was
    an apprentice in the Ministry of Defence, UK.

    This technology/terminology is NOT NEW- martensite is one of the 3 phase changes
    in steel alloyed with other metals, I looked it up; “Stainless steels may be classified by
    their crystalline structure into three main types: Austenitic, Ferritic and Martensitic”
    Remember the phase diagram with the triple-point, anyone?

    Sounds like this is a development of older metallurgy. Have I got this wrong?

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