[scientizscht (OP)]

Hello

I want to have a rod of a material. Is it possible to make this rod flexible or rigid on demand? Without having to melt it or freeze it.

Thanks!

[wolfekeeper]

If you're a man, yes.

There's also magneto-rheological and electro-rheological fluids that can do stuff a bit like that, but they're not metals.

And there's also non-Newtonian materials like Oobleck.

[scientizscht (OP)]

Isn't there anything that gets hard like cement?

But not liquid, I want it solid.

[mbaker335]

I would say copper fits the bill. It will work harden if hammered or a rod is bent back and forwards. At the point where it hardens it gets brittle. Heat, I believe, will make it permanently softer again but no where near the melting point.

[chris]

magneto-rheological and electro-rheological fluids

Very good point; are there not some metallic materials that will behave as a non-Newtonian fluid?

[scientizscht (OP)]

magneto-rheological and electro-rheological fluids

Very good point; are there not some metallic materials that will behave as a non-Newtonian fluid?

Yeah but these are liquids.

[diogenesNY]

Nitnol might be somewhat close to what you are seeking.

http://www.specialmetalalloys.net/nitinol.html [nofollow]
https://en.wikipedia.org/wiki/Nickel_titanium [nofollow]

diogenesNY

[Petrochemicals]

With anything exept heat is the question? Electric magnetism etc?

Edit.

There are plastics that are solid in the case of inpact that soften afterwards. Bit i think if a metal exists, its probably a military secret. How soft is soft, hard is hard, and metat is metal ?

https://www.explainthatstuff.com/energy-absorbing-materials.html