Shock‐Induced Substructural Changes in Prestrained Iron

Deformation structures of iron samples prestrained to various amounts prior to their exposure to 50 and 100 kbar shock waves have been examined by transmission electron microscopy. On shocking, the regions which had deformed during prestraining exhibit dislocation configurations characteristic of large‐strain room temperature deformation, and the undeformed areas develop substructures representative of very low‐temperature conventional deformation. Interactions between shock‐induced dislocations have also been analysed. Passage of a 100 kbar shock wave through samples prestrained 20% causes localized recrystallization. Experimental evidence favours the formation of nuclei for recrystallization by the coalescence mechanism.