| For what it's worth.....and all that jazz.
When you freeze a material, atomic motion does decrease. However...for a material to actually have it's atoms or molecules actually move in to fill out voids, etc., it is necessary that you heat the thing so that the activity INCREASES; this increase in activity allows the material to smoothen out the bumps (or discontinuities in the crystalline structure)... No, we're not talking about scratches and stuff...we're talking about the actual shape of the crystals of the parent materials (ferrite, carbon, so forth and so on).
You then slowly cool the material so that the crystals are allowed to "settle in" to their new, lower energy (or lower stress) locations. This is called "annealing".
I've heard it said (can't find the reference right now) that super cooling does have an effect on steels....but steel is vastly different from brass in that the carbon in steel does not actually "blend" with the ferrous but rather sits in the spaces between the ferrous "crystals". It is the movement and location of the carbon that affects how "hard or soft" a steel will be. (In conjunction with the grain SIZE of the ferrous crystals).
Brass, on the other hand, is a very homogenous mix of copper and zinc with NO carbon involved. And don't forget that brass instruments also are soldered which introduces a different variable...the tin and lead in the solder.
I once found a neat website that had all kinds of information on annealing etc. and included microphotographs of a brass structure with different degrees of annealing applied. If I find it I'll add it to this thread. |