Strain-Induced Effects on Interactions of Non-Metal Atoms Introduced in Metals Having H.C.P. Structure. 2. Interstitial Atoms on Tetrahedral Interstitials

摘要

We consider the analytic peculiarities and singularities of various interactions between hydrogen-isotope (H,D) atoms located at octahedral interstices in an h.c.p. metal Me (Me = #alpha#-Y, #alpha#-Sc, #alpha#-Ti, #alpha#-Zr) with taking into account its atomism, anisotropy of elasticity, and 'size' effect. The interaction between H(D) atoms, caused by distortions they induce into the h.c.p. Me, is studied by the lattice-statics method in a quasiharmonic approxmation with taking into account the noncentral character of ('pairwise') interatomic H(D) - Me interaction. The microscopic energy parameters of 'direct' H(D) interactions are estimated using a semiempirical approximation. It is shown that the energy of an 'orderable' h.c.p. - Me - H(D) (#alpha#Y-H, #alpha#Sc-D, #alpha#Ti-H, #alpha#Zr-D) solid solution in (meta) stable single-phase states cannot be estimated adequately without taking into account the strain-induced interaction between H(D) atoms as an additional contribution to their 'electrochemical' interaction. The results of calculation indicate, for instance, a tendency of the #alpha#Y-H and #alpha#Sc-D solid solutions for the short-period ('orientational') ordering, unlike a tendency of the #alpha#Ti-H and #alpha#Zr-D solid solutions to form, generally speaking, the nonstoichiometric subhydrides (subdeuterides) having the ordered crystal structures which show superlattice reflections in diffraction patterns in the special point M (centres of the rectangular faces of the first Brillouin zone) of the reciprocal space of the h.c.p. lattice of sites.