It was noted that published data on the mechanism of internal friction maxima, produced by O, N, and C in α-Ti, α-Zr and α-Hf, were contradictory. They did not indicate what type of complex induced relaxation: interstitial atoms or interstitial atoms with substitutional atoms. In order to settle this question, modeling of the short-range order and atomic displacement fields around solute-atom clusters was carried out by applying the Monte Carlo technique to typical Ti–O–Zr alloys. The energies of strain-induced (elastic) O–O and O–Zr interactions, and the displacement fields of host atoms around the solute atoms, were calculated. The concentration dependence of the relaxation strength, due to the diffusion under stress of O atoms, was evaluated by using the values of local displacement around the solute-atom complexes. It was shown that the developing short-range order could not be described by single O–O or O–Zr pairs, nor the associated relaxation as being simple reorientation of atomic pairs. It appeared that, in many cases, the internal friction was caused by more complicated clusters; made up of interstitial and substitutional atoms.

Interaction of Dissolved Atoms and Relaxation due to Interstitial Atoms in HCP Metals. M.S.Blanter, E.B.Granovskiy, L.B.Magalas: Materials Science and Engineering A, 2004, 370[1-2], 88-92