Wave attenuation in microcrystal copper at irradiation by a powerful electron beam

The numerical study of high-rate plasticity of Cu target with different grain sizes under the action of nanosecond relativistic high-current electron beam has been carried out in the paper. The model of microcrystal material plasticity includes dislocation kinetics and dynamics as well as the stress relief in the grain boundaries of the polycrystal. This model has only two adjustable parameters. The presented results demonstrate a strong dependence of the shock wave attenuation coefficient on the grain size. At the grain size of about 70 nm, the plasticity mechanism of the dislocation glide inside grains changes to plasticity mechanism along grain boundaries.

► Plasticity of microcrystal material is caused by dislocations and grain boundaries.
► At high strain rate the grain boundaries are similar to a very viscous liquid.
► The grain size dependence of plastic properties is not uniform.
► A maximum of dynamic yield strength exists at grain size less then 100 nm.
► Shock wave attenuation coefficient is a grain size dependent parameter.