Hugoniot Equation of State of Aluminum and Steel from Oblique Shock Measurement

Abstract

A method using an explosive-produced oblique shock in a wedge-shaped specimen has been developed for determining the Hugoniot equation of state of solids. Simultaneous measurements of shock and free-surface velocities along the wedge face permit calculation from a single shot of pressure and density over a pressure range exceeding 2:1. Aluminum has been studied over the range 40–180 kb, good agreement being obtained with the normal-shock method. The data for low-carbon steel may be qualitatively interpreted in terms of a double-shock system, associated with the polymorphic transition from α- to γ-iron proposed by Minshall and Bancroft. The present method may provide a means for measuring the pressure at which a solid undergoes a polymorphic transition under dynamic conditions. Preliminary results for antimony indicate a dynamic phase transition at 95 kb corresponding to the one observed statically at 84 kb.