3663.     ---------------.  [WERT, C. A.]  Diffusion Coefficient of Carbon in Alpha-Iron.  Phys. Rev., vol. 79, 1950, pp. 601-605; Chem. Abs., vol. 44, 1950, p. 9760.

        Equation of the form D=D_oe-^∆H/RT is developed for interstitial diffusion in cubic lattices.  This development uses a classical statistical mechanical treatment.  Measurements of D for C in a-Fe were made, -35° to 200°.  Combined with earlier data they extend the knowledge of D in this system from D=10^-20 to D=10^-6 cm.² per sec.  The values of D_o and ∆H obtained by fitting this equation to the experimental points give D_o=0.02 cm.² per sec. and ∆H=20,100 cal. per mol.