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How to let the cold work shape memory alloy to acquire shape memory properties

  1. Mar 10, 2010 #1
    I have a cold work Nitinol wire, my supervisor ask me to do heat treatment at 700 degree celcius after that quench in ice water.He tell me that after heat treatment, the wire will acquire the shape memory properties, but i have repeat for few sample the wire could not function. when i put the deform wire inside the hot water,it not back to their preset shape. what is the problem?
  2. jcsd
  3. Mar 24, 2010 #2
    Years ago I played around with Nitinol. It worked great!
    What might have happened is that you forgot a step.

    Step1: Take a straight piece of Nitinol wire and bend it, say in half.
    Step2: Keeping it bent, say, with a pair of pliers, heat it to the required temp.
    Step3: After cooled down, BEND IT BACK TO A STRAIGHT WIRE or any other shape.
    Step4: Toss that wire into hot water and it will snap back to the "bent" shape of Steps 1&2

    Perhaps you missed step 3
  4. Apr 7, 2010 #3
    I found it possible to be quite crude about it.
    I first wound the shape and clamped it, then ran a current through the wire until it relaxed. It did glow red.
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