[Phys-L] Iron density question

[bernard cleyet <bernard@cleyet.org>]

I just returned from the NorCal/Nevada AAPT section meeting, where i 
demonstrated the allotropic change in Iron using a video clip from the dining 
room table.  

If unfamiliar,  here:  


http://www.cleyet.org/allotrope.mov  


It clearly shows the change in density.  The wire likely wasn’t very pure, 
which, I assume, makes the change less sharp and “intense”.  


So my question is:   Is QM necessary to explain or can simple electrostatics 
explain?  If simple electrostatics does, then I’d expect the FCC form to be 
less dense than the BCC form, no?  

Note: on cooling it passed from more dense to less dense.  Also why does one 
structure dissolve carbon more?  Seems obvious. 

bc … to lazy to search which is BCC, etc.;  austenite or ferrite, and he uses 
scare quotes when he can’t remember the correct word.  

p.s.   I don’t remember the text explaining when I taught engineering materials 
at the local community college.