α-phase Hugoniot of iron

Abstract

The published data on the α-phase Hugoniot of iron have appeared to indicate a ’’softening’’, relative to expected behavior, of the Hugoniot as the phase-transition stress of 13 GPa (130 kbar) is approached. This has been interpreted as evidence of a partial early transition to the high-pressure ε phase in shock experiments. A careful reexamination of the available data and data reduction procedures reveals that the α-phase Hugoniot of iron appears to be quite normal to 13 GPa, and therfore the Hugoniot data give no indication of an early partial phase transition. The Hugoniot data are fit by the linear shock-velocity–particle-velocity relation U=C0+1.33u, where C0=4.63 mm/μsec.