High strain rate deformation of Mo and Mo-33re by shock loading: Part I. Substructure development

Abstract

The details of substructure development in Mo and Mo-33Re deformed at ultrahigh strain rates by shock loading have been studied quantitatively with optical, electron optical, and X-ray diffraction techniques. The finite rates of dislocation generation, apparently limited to rates of the order of 10 21 m−2 s−1, cause shock-induced dislocation densities to decrease at short shock pulse durations for a constant shock pulse amplitude. Similarly, the volume fraction of deformation twins in Mo-33Re also decreases at short pulse durations. Twin thicknesses were found to be 32 nm and 200 nm for Mo-33Re and Mo, respectively, with these thicknesses independent of pulse duration. Measurements of the dislocation loop densities support the concept of loop formation by a dislocation mechanism, rather than through the agglomeration of shock-induced excess point defects.