DISLOCATION MOTION IN VA METALS STUDIED BY INTERNAL FRICTION

Abstract

Dislocation motion in Va metals, V, Nb and Ta at low temperatures was studied by internal friction and dynamic modulus measurements. The results on pure and impure Nb and Ta support the assignment that the δ and α peaks are intrinsic dislocation relaxation peak and H cold work peak, respectively. Dislocation motion below the δ peak temperatures at say 9K was discussed based on the observed effect of deformation and H charge on modulus defects at 9K. Modulus defects at 9K were considered to be mainly due to kink diffusion along screw and non-screw dislocations and the δ peak was considered to be associated with double kink formation on non-screw dislocations. H charge suppressed the modulus defects at 9K and seemed to induce a very strong dislocation pinning which is stable up to room temperature. Other types of dislocation pinning observed in V after quenching the specimen deformed and H charged were also shown.