The bulk diffusion of P in liquid-quenched amorphous alloys was studied by measuring the kinetics of P segregation to the free surface. The diffusion rates in the material obeyed an Arrhenius relationship,

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

and the results were also the same as those for P diffusion in bulk Fe. The activation energy for diffusion suggested that P diffusion was not the primary mechanism controlling  properties such as stress relaxation in such materials.

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