Material Question

Because I'm a material girl~

But seriously. Something I have been pondering on for the last few minutes more or less has eluded me. I see two instances of materials with the "Perfect" moniker. Perfect Iron, and Perfect Diamond. Don't get me wrong, I'm happy we have lots of alternatives to the basics, and more or less the fact I remember them. I was wondering, what makes them so good? Or rather, what makes them so good, and why do they lack descriptions? That and Carbon Ring.

They are considered "ideal" by the forum at large because they have both have a very high strength in the line of the crystal structure. In actuality they would be fairly fragile since all their strength is, by their nature, focused in only one line, making them prone to cracks and such.

That is why in metallurgy you try to make the grain size (a grain being a region with the same crystal alignment) of a alloy very small so that the overall grain of the material is more random to prevent such weakness. In a composite these 'perfect' materials would be useful since you arrange them in such a way that the majority of forces would be on their strong axis, but they would perform very poorly as a solid, pure material.

As a additional note, diamond ('perfect' or otherwise) is actually not a great 'all purpose' armor material (as it is used in many items) because diamond 'burns' (converts into simple graphite) at a relatively low temperature (1700 *C in a oxygen-free zone or 800*C in a atmosphere containing oxygen).

wouldn't it still make for a good body armor though?

As a composite yes, but it would perform terribly as a pure solid.

A example in use today would be something like Kevlar (or carbon nanotubes). It is relatively weak to forces acting on any axis other than its long axis but when arrayed in a weave or composite, where the arrangement of the fibers serves to put the majority of any forces on the long axis (since with a impact the material will tend to stretch, which will act on the long axis of the fiber) and thus the aggregate material is very strong.