The binding energy of oxygen to a dislocation in tantalum

Abstract

The binding energy between an oxygen atom and a dislocation in tantalum has been determined experimentally by measuring the critical temperature, T _c, a t which the discontinuous yield disappears on heating. Assuming that T _c is the temperature at which the atmosphere is boiled off and estimating the saturation concentration, C _s, of oxygen at a dislocation from the analysis of Cochardt, Schoek and Wiedersich, using a value for the lattice distortion surrounding an oxygen atom deduced from x-ray measurements, the binding energy V _B is found from where C ₀, is the concentration of oxygen at a large distance from the dislocation. As an example of the use to which a knowledge of the binding energy can be put, the theoretical shear strength of tantalum is estimated to be G/9·8 (G is the shear modulus) by a method which does not require the assumption of a specific law of interatomic forces.