Correlation effects in gas absorption by binary ordered alloys

The equilibrium concentration of a gas dissolved in a binary ordered alloy with bcc lattice in the presence of short-range order in both the host system and in the system of host and impurity atoms is computed. It is shown that the correlation in filling the lattice sites by atoms of the alloy is manifested in the solubility only because of the volume effect associated with the dependence of the host and impurity atom interaction energy on the lattice parameter. In alloys in which the solubility increases in the disordered state with rise in temperature, a solubility extremum can be observed in the area of the order-disorder transition point because of the change in the degree of long-range order upon the introduction of the third component. If the transition into the ordered state is accompanied by the growth of absorption, a maximum appears in the temperature dependence of the solubility, otherwise a minimum. Singularities in the solubility associated with the gas not being ideal are examined.Presented at the All-Union Seminar on Hydrogen in Metals (Donetsk, 1977).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 75–82, February, 1978.