METALLURGICAL CHARACTERIZATION OF ATLAS CYLINDRICALLY CONVERGENT SPALLATION EXPERIMENTS.

The microstructural distribution and nature of damage from three different cylindrically convergent spallation experiments performed on the pulsed power machine named Atlas are presented. Longitudinal momentum trapping was used to minimize the influence of release waves and thereby decrease the dimensionality of the experiments. Two of the experiments involved soft capture of the spalled piece. The material used is a proprietary directionally cast Al alloy with a mostly equiaxed grain morphology and essentially random texture in the region of spallation. The damage was most distributed in the lowest impact velocity shot and became progressively more narrow with increasing impact velocity. The effectiveness of the momentum trap design increased with increasing impact velocity.