|MadSci Network: Physics|
Hi there! A liquid metal is a jumbled soup of metal atoms whose individual kinetic energies exceeds the bond energy that the atoms use to link up when in a solid state. As liquid metals cool (i.e. as atoms lose their kinetic energy) atoms within a liquid can latch onto neighbouring atoms and start to form crystalline lattices. These are networks of atoms arranged in a regular, ordered sequence, whose layout depends on the number of bonds that each individual metal atom can form. It is at least theoretically possible to cool a tank of any liquid metal to form one single crystal. However, in practical terms, usually many smaller crystals start to form throughout the liquid. Each of these crystals grow as cooling spreads, in different orientations, eventually giving rise to a polycrystalline ("many crystal") structure. Naturally the junction between crystals is typically weaker than the crystals themselves, so care has to be taken when casting metals (that is, turning them from liquid to solid) in order to produce a solid metal with the desired properties for a particular use. All metals are crystalline as solids, in that they are made of crystals, but generally all metals are polyscrystalline when solid (made of more than one crystal). Liquid metals can form perfectly crystalline solids, but in practical terms they rarely do so. I hope this helps to clear up your confusion. Andy Goddard
Try the links in the MadSci Library for more information on Physics.