Nitinol paper clip returns to form after bending - GIF

[Jon]

Nitinol paper clip returns to form after bending.

[mklotz]

I'm surprised that nobody has asked the obvious question...

How was the paper clip shape formed in the first place? Why doesn't the wire return to whatever shape it had when it was first manufactured?

[Frank S]

Interesting wiki on nitinol

https://en.wikipedia.org/wiki/Nickel_titanium

[Frank S]

Too bad the manufacturing process it difficult and expensive. could you imagine a vehicle mad out of the stuff then after an accident the only thing required to straighten it out would be to apply heat in varying degrees judiciously to the effected areas A simple infrared heat lamp would replace 1000'S of dollars worth of specialty tools
As many accidents as my first wife had it would have saved me a lots of money that woman could figure out how to wreck a car in an open field with out even starting the engine.

[Jon]

After a little poking around, I believe that there are different methods to imprint a form, usually involving very high heat. The shape changing has something to do with shifting among different crystalline structures. More: https://en.wikipedia.org/wiki/Austenite , https://en.wikipedia.org/wiki/Martensite

I searched for "nitinol" at the US patent site; 69 patents listed: Patent Database Search Results: TTL/nitinol in US Patent Collection. Looks like the most common use is in medicine: stents, catheters, suturing tools, etc.

Some example patents:

Nitinol Ring Marmon Clamp


Nitinol Ice Blades


Nitinol Loop Suture Passer


Flexible Drill and Method of Joining Nitinol to Dissimilar Metals

[mklotz]

I'm forced to wonder what would happen if you cut a piece of nitinol wire in two and then put the cut ends in close proximity in some hot water.

Fascinating stuff and provides endless inspiration for time-wasting gedanken experiments like is a nitinol Stirling engine possible?

[owen moore]

I read somewhere that this wire is used or was proposed to be used for arterial stints, as it could be inserted into the blood vessel in a collapsed state and body heat would wake it up into it's fabricated shape.Interesting stuff, and expensive.

[f800]

We use nitinol heart valves for aortic valve replacements. Fold up, insert through groin and fish up into the heart, then deploy. Truly revolutionary vs traditional sternotomy incision. Only 2 pokes in the groin

[PJs]

I'm forced to wonder what would happen if you cut a piece of nitinol wire in two and then put the cut ends in close proximity in some hot water.

Fascinating stuff and provides endless inspiration for time-wasting gedanken experiments like is a nitinol Stirling engine possible?

A Lab Tech (Ridgway Banks) from Livermore Lab came up with several patents on NiTiNol engines. I know, the whole free energy thing, but the engines are interesting designs. The video at the bottom of the page shows his first proto and some of the things the found about the longevity and strengthening properties over time. Worth the watch imho...even though its from 1982.

I've been thinking about some uses around its conductivity properties after visiting my sons work place a few weeks ago and seeing some of the biomedical applications he's working on. Tiny Tiny stuff like a ball valve about ø.7mm x ~5mm long and NitiNol coils about 2-3mmOD.

Definitely cool metallurgy and physics and a great rabbit hole for those inclined.