Dynamics of plastic bending of whiskers, induced by bombardment by a dense electron beam

Abstract

We report new results from experimental investigations of the strong plastic bending induced in whiskers by nanosecond pulsed bombardment by a dense electron beam. The bending dynamics has been traced for the first time by means of a VFU-1 high-speed movie camera synchronized with a powerful small GIN-600 electronic accelerator. The measured duration of the plastic bending process for whiskers 40–100 μm in diameter was 1–2 msec. This is of the same order of magnitude as the characteristic relaxation time of the quasistatic mechanical stresses that are formed under uneven bombardment because of temperature gradients and disappear when the temperature is evened out by heat conduction. The measured bending dynamics was found to be nonmonotonic and rather complicated. After a nanosecond pulse of bombardment by a strong electron beam the bending of the whisker at first increases, then decreases, increases once again, and finally is saturated at some final value during flexural damping vibrations. The experimental data are discussed on the basis of the dislocation theory of plastic bending.