On the stress–subgrain size relationships derived from the composite model of dislocation structure

The present paper discusses a derivation of the stress–subgrain size relationship from the composite model of dislocation structure presented recently by Raj and suggests modifications of the original assumptions. The modified version is compared with another stress–subgrain size relationship based also on the postulates of the composite model. Both relationships give the subgrain size as a function of reciprocal applied stress and of two quantities inherent to the composite model, namely the volume fraction of the hard regions and the local stress in the hard regions. The predictions of the relationships based on X-ray data are compared with experimental data resulting from direct TEM observations.