Friccion interna debido a la interaction entre dislocaciones y atomos solutos

Abstract

A theory is developed to explain an internal friction peak which is observed after cold-work in b.c.c. metals containing impurity atoms in interstitial solute solution. In contrast to previous assumptions it is proposed that the elastic relaxation is directly caused by the movement of dislocations. The dislocations are normally locked by impurity atmospheres but can move at the peak temperature by dragging the solute atoms along. The dislocations are assumed to be anchored at immobile precipitates or clusters of solute atoms distributed at intervals along the dislocation line. Two limiting cases of dislocation oscillation are considered with amplitudes large and small compared with the interatomic distance b. It is found that the peak height and the relaxation time (and hence the peak temperature) depend on structural details such as average free length between precipitates, their distribution function and the concentration of solute atoms.