'Conservative climb' of a dislocation loop due to its interaction with an edge dislocation

Abstract

A new type of dislocation motion, called 'conservative climb', has been observed in zinc platelets deformed in tension inside an electron microscope. Circular, prismatic dislocation loops are often forced to climb out of their glide cylinders by their repulsive interaction with edge dislocations. It is observed that the area inside a loop is conserved during its movement, from which it is concluded that the climb occurs, not by self-diffusion, but by the transfer of vacancies around the loop by pipe diffusion. Calculations of the interaction energy, of the total form on the loop, and of the forces per unit length on the elements of the loop show that conservative climb can be expected to occur when the temperature is not too low and the separation of loop and edge dislocation is small.