[Noisebridge-discuss] First Post: Non-Hg Liquid Metal

[Noah Balmer]

It is fairly uncommon for liquids to expand when they fuse.  I think bismuth
does the same thing, and water does, as you mentioned, but don't know of
anything else offhand.  In the case of water it has to do with a crystal
structure that requires more space than the amorphous liquid does*.  I don't
know what the mechanism is with gallium.  It has conchoidal fracture, which
is commonly seen in amorphous glassy solids, so I think it may be some other
mechanism, but it may just be a very fine grained crystalline structure.

-N

*Water molecules are approximately L-shaped.  When they can flow feely
around each other they can spoon and hook around each other in all sorts of
ways that increase the density.  When they are frozen into a regular grid,
the inside of the L is empty, so they are packed less densely.  Pressure on
ice near the melting point can disrupt the crystal structure and re-liquify
it, which is one of the reasons ice skates work so well.  A gallium skating
pond might work too, though gallium loves alloying so much it might just
dissolve the blades (it dissolves aluminum readily, don't bring it on a
plane!) , and in its liquid form it's kind of sticky.


On Fri, Jun 5, 2009 at 3:48 PM, d p chang <pchang at macrovision.com> wrote:

> Noah Balmer <noahbalmer at gmail.com> writes:
>
> > I'm surprised to see it stored in a glass vial in that image
> > though, because it expands by a few percent when it solidifies, and
> > will often break rigid containers.
>
> wow. i thought water was 'weird' that it expanded when it became a
> solid. am i just mis-remembering something or is this actually common?
>
> \p
> ---
> I know that you believe that you understood what you think I said, but I
> am not sure you realize that what you heard is not what I meant.
>                - Robert McCloskey
>
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