I am wondering why molten metal in a vacuum of electron beam and machines never turns to gas like liquid water does when exposed to a vacuum.
In a nutshell, the bonds between Iron molecules is much stronger than between water molecules. Iron's sublimation temperature in a vacuum is (I couldn't find exactly), but around 500 degrees C on the chart (below). At 1 ATM vaporization temp is much higher, a bit over 2,500 C. It won't stay in vapor form unless the atmosphere is above a certain temperature/pressure threshold that we don't see very often. I would imagine an electron beam could vaporize Iron, but it wouldn't stay vaporized very long.
Without an Electron beam, Iron would need to be in a hot vacuum to vaporize. In our solar system, Iron would probobly have to be a little bit closer to the sun than Mercury to be at vaporization temperature.
Source, Wiki (I'm afraid). http://en.wikipedia.org/wiki/File:Pure_iron_phase_diagram_%28EN%29.png