The spalling of aluminium with a pulsed electron beam

Energies of up to 3 kJ g⁻¹ were deposited in thin aluminium foils by means of a pulsed electron beam with a duration of 35 ns. The subsequent expansion of the foils was observed using high-speed photography and compared with that predicted from numerical solutions of the equations of motion. The velocities observed were about double those calculated. The limitations of the expansion equation of state used in the calculations are discussed.The variation of the spall strength of aluminium with temperature was derived from the measured energy deposition thresholds to spall foils of different thicknesses. It was found to fall from 12·5×10⁸ N m⁻² (12·5 kbar) at 350°C to about 4×10⁸ N m⁻² at 600°C with some evidence for a strength in the solid-liquid phase of a fraction of a kilobar.