Is there any work that has been done on the effects of vibration on the
formation of crystal in solidification of metals and alloy's? By
vibration I mean sound at various frequencies from subsonic through
ultrasonic. Would such vibration help crystals form by jiggling atom so
as to have them find their lattice spots more easily. Would that help
welds be annealed?
Yes - plenty (check out journel "ultrasonics" also G.J. Eskin wrote a book
on it Google Ultrasonics+metal+casting.
Sound effect are typically called "insonation" in regards to the use ultras
onics in casting and metal working (decreasing metal friction etc).
As for "jiggling atoms" check out "hypersonics" in the GHz range - the trou
ble comes in when phonons (sound particles)are at such high frequency (to m
ake a wavelength small enough to effect an individual atom) it is "heat" an
d has an exceedingly high dispersion i.e. only atoms in thin films can be d
irectly effected - if at all. Atoms are "held" together by the lack of hea
t - so they naturally "find their lattice spots" very easily - it just rand
om phonons that cause the trouble.
As for welding a company called "Bonal Tech"
that still sel
ls an eccentric drive electric motor on a magnetic base to stress relieve w
Hope that helps
The quantum energy of a thermally excited phonon is very low,
E = h nu = k T. But I think, a vibration mode can be excited to contain
many phonons. This in turn means there are two populations of vibrations
with different temperatures; those excited by heat are at the ambient
temperature while those driven by a sound generator are at a higher
temperature. Is there any way that the high temperature vibration can
jiggle the atoms that the thermal vibrations cannot? Ultimately, the
high temperature vibration heats up the entire lattice as its phonons
transfer energy to unexcited vibrations by collision.
If "Thermal photons" are of low energy how can we melt metals with heat?
Quanta of heat (phonons) are the transfer agents of energy to atoms that ca
n break the "electron glue" holding metals in crystalline state (condensed
matter)causing them to melt, then boil, then turn to plasma and finally to
Plank heat (black hole heat) - the more phonons there are the higher the t
Do you believe there are several population of phonons at different tempera
tures? If so does it not violate your equation E = h nu = kT ?