The orientation relations between the α and ω phases of shocked zirconium

Abstract

From the recent shock wave measurements on Zr, Song and Gray (SG) reported a new orientation relationship (OR) between α and ω phases, which differed from those observed in earlier hydrostatic pressure experiments. Based on this, a different transformation mechanism was also proposed. To clarify the situation, we have performed selected area electron diffraction measurements on Zr samples shock loaded to 12 GPa. All the diffraction patterns are found to be consistent with the OR of Usikov and Zilbershtein (UZ). One diffraction pattern revealed even the OR of SG also. The superposition of the stereographic projections shows, however, that the ORs of UZ and SG are equivalent. Thus, the mechanism of phase transformation under static and shock loading is identical. Also, as both models (proposed by UZ and SG) lead to equivalent ORs, it is difficult to establish which one is operative.