It is very possible to form crystal lattices using a mixture of different
elements, especially with metals. In fact, some alloys (eutectics) exhibit
the same phase behavior as pure metals. Iron is generally an easily
alloyed metal, probably due to the fact that it switches crystal structures
(between BCC, FCC, and HCP) easily under fairly mild conditions. As for
amorphous crystals, I don't think metal crystals can be amorphous. If I am
not mistaken, amorphous crystals can only occur when there is little or no
electron mobility in the lattice, which is not the case with metal crystals.
Additionally, high temperature/pressure environments are *ideal* for large
crystal growth. The high temperature means the atoms have enough energy to
organize, and the high pressure strongly encourages the formation of large
crystal lattices. When you consider that the core pressure is around 50
million psi, it would be nearly impossible for amorphous crystal structures
to occur, especially when you have the atomic mobility that occurs at a
temperature of 5000-6000 C.
-James Rogers
jamesr@best.com