The bulk diffusion of P in sputter-deposited and liquid-quenched amorphous samples was studied by measuring the kinetics of P segregation to the free surface. The results could be described by:

D (cm2/s) = 7 x 10-2 exp[-1.95(eV/atom)/kT]

and were the same as those for P diffusion in bulk Fe.

D.R.Baer, L.R.Pederson, M.T.Thomas: Materials Science and Engineering, 1981, 48[2], 283-90