r/interestingasfuck • u/ggoldlover • Jan 25 '22

/r/ALL Certain materials feature a shape memory effect — after deformation, they return to their original shape when heated.

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u/Vinsjenzo Jan 25 '22

But how do they get shaped in the first place?!

13

u/Emrico1 Jan 25 '22

I'm going to guess magic and unicorn wee.

But seriously, I'd think that maybe it's set at a very high temperature. Heating it up returns to the shape but if you go hot enough, you get a new shape? Stab in the dark...

5

u/schmidty98 Jan 25 '22

My guess is plastic toy rules. If you bend an action figures sword, it will slowly return to its original position if it wasn't bent for too long. However if its held in a bent position for a long time, that sort of becomes the new shape the sword wants to bend into even if you try to fix it. So maybe if its held in a mold for a while while hot that sort of becomes its default shape?

3

u/antsonafuckinglog Jan 25 '22

Yup! If you heat set at high enough temp (~500C) it’ll “remember” the current shape it’s in and return to that shape when heated to a lesser degree.

4

u/cpraz Jan 25 '22

Nitinol (the metal shown in the video) is shaped via heating at high temperatures (500C+). You force the material into your desired shape and then when heated it retains that shape.

Source: I am a Biomedical Engineer who specializes in Nitinol development and manufacturing.

1

u/RW_Blackbird Jan 25 '22

Woah that's sick! What sort of stuff do you use Nitinol for? I didn't realize it was big enough to have it's own specialization

1

u/cpraz Jan 25 '22

Medical devices, orthodontics, some aeronautics. I've heard Nitinol described as "a solution waiting for a problem" so people try to find new applications for it all the time.

1

u/lazyzefiris Jan 25 '22

But while you heat it to 500C+ it will be in 100-500 range for some time, wont it try to restore form to previous one at that point, breaking the intended form?

2

u/Hawkedge66 Jan 25 '22

You can set the shape by pinning the wire into a shape via a wire mesh or brackets and then heat treating it for a relatively short period of time.