It was recalled that experimental and theoretical evidence indicated that the problem of the Peierls stress in these metals might be due to the existence of several types of kink pair formation mechanism with very different activation energies. These problems included a discrepancy between the Peierls stress values which were deduced from Bordoni damping peaks and from yield stress measurements. Also, very high concentrations of vacancies (and an absence of interstitials) were generally observed after plastic deformation. Very low temperature softening was sometimes observed after cold working or after irradiation. It was suggested that interactions between intrinsic point defects (vacancies, self-interstitials) and the split dislocation cores could be responsible for the various kink pair formation mechanisms.

G.Gremaud, B.Quenet, W.Benoit: Journal of Alloys and Compounds, 1994, 211-212, 111-3