THERMODYNAMICS AND DIFFUSION BEHAVIOR OF INTERSTITAL SOLUTE ATOMS IN NON-PERFECT SOLVENT CRYSTALS

The effect upon the thermodynamic functions and diffusion behavior of the interaction of interstitial solute atoms with lattice discontinuities has been calculated. The calculations are based on first-neighbor first-order statistics and the absolute rate reaction theory. It is shown that the calculations are consistent with the observed behavior of hydrogen in b.c.c. iron if it is assumed that the iron contains a density of 'trapping' sites in the range 10-6-10-3 such sites per Fe atom and the depth of the sites is ~ -27 kJ/mole. The form of the distribution function relating the ratio of the number of solute atoms in 'normal' lattice sites to these located in 'trapping' sites to temperature is a modified Fermi-Dirac function. © 1979.