Influence of temperature on dissociation of dislocations and plastic deformation in spinel oxides

Abstract

Depending upon the temperature at which spinel oxides are deformed, different dissociation configurations of dislocations have been observed. At elevated temperatures, edge dislocations are dissociated over several hundreds angstroms by a process involving climb of partials. At low temperatures, the long screw dipoles resulting from indentation tests suggest a classical dissociation of dislocations out of the preferred glide plane. These effects are compared to calculations of stacking-fault energy in the spinel structure. A good qualitative agreement is found whatever the dissociation mechanism. Quantitative agreement is satisfactorily obtained only in so far as glide dissociation is concerned. Discrepancies between calculated and observed climb dissociation suggest a strong interaction effect with point defects. The possible effects that such a dissociation dependence upon temperature has on deformation mechanisms in spinels are discussed.