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What sort of a microstructure would you get on bubbling Aluminium vapors through a large tank of Helium?

Would it be a glassy microstructure and/or would you get nano-powders? and/or a new crystal structure formation because of the excess helium which would be present in the aluminium matrix? Ignore metal coolant reactions, if any.

Aluminum vapour would consist of Aluminium atoms, unlike liquid aluminum which consists of clusters. So, on rapid cooling from gas to solid, would you still get an FCC crystal structure for aluminium? (There would be no time for diffusion)

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    $\begingroup$ Your question really what if you rapidly quench aluminium. It would had to get vapours anywhere near the liquid helium. Liquid helium would be a problem it would explode with gas evolution and the gas layer would restrict cooling. $\endgroup$ – user2617804 Dec 20 '13 at 14:59
  • $\begingroup$ What I really want to know about is this: Aluminum vapour would consist of Aluminium atoms, unlike liquid aluminum which consists of clusters. So, on rapid cooling from gas to solid, would you still get an FCC crystal structure for aluminium? $\endgroup$ – Ash Dec 20 '13 at 15:24
  • $\begingroup$ There are plenty of actual products made by aluminium vapour deposition. So the question should be easy to answer by looking at the structure of the deposited aluminium. $\endgroup$ – matt_black Dec 20 '13 at 16:10
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There are a number of actual production processes that involve coating surfaces with metals via what are effectively vapour-phase metals.

Sputtering seems to be preferred to simple evaporation because it gives better results and allows for better control over the properties of the deposited metal coating (or non-metal, a very wide variety of compounds can be deposited this way including some created by vapour phase reactions). Sputtering creates aluminium (the same applies to many other elements or compounds) vapour by bombarding solid aluminium with inert atoms and allowing the atoms to hit the coated surface.

There don't appear to be any unusual crystal structures in the resulting coatings, though the grain size and other factors can be controlled by altering the conditions.

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