Laser-Induced Shock Compression of Copper and Copper Aluminum Alloys

Abstract

Single crystal copper and copper 2‐wt% aluminum alloy with [1̄34] and [001] orientations are compressed by means of a high energy short pulse laser. Pressures ranging from 20 GPa to 60 GPa are achieved. The shocked samples are recovered and the residual defect substructure is analyzed by transmission electron microscopy. Results show systematic differences depending on orientation and stacking fault energy. Samples with orientations [001] are symmetrical with simultaneous activation of eight slip systems. This leads to a higher work hardening rate. The [1̄34] orientation is asymmetrical with one dominating slip system, and thus a reduced work hardening rate due to a prolonged easy glide region for dislocations. These differences in work hardening response affect the stresses required to achieve the twinning threshold pressure. The effects of stacking fault energy on the defect substructure and threshold twinning are also characterized. Experimental results are rationalized in terms of a constitutive description of the slip‐twinning transition using a modified MTS equation. Differences in the mechanical response of the orientations and the chemical compositions are responsible for differences in the shear stress in the specimens at the imposed pressures and associated strains.