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Abstract:
Ultrafast (130-fs) x-ray diffraction at the Linac Coherent Light Source has been applied to observe shockmelting, which is driven by a rapid (120-ps) laser pulse impinging on a thin (few micrometers) bilayer ofaluminum/zirconium. At a pressure of 100 GPa in the aluminum (130 GPa in the zirconium), there is rapidmelting of both metals and the recrystallization of zirconium into the bcc β phase. We observe the solidificationof the melt starting a few hundred picoseconds following the shock melting, out to 50 ns when the zirconiumis fully crystallized into the bcc β phase at a residual temperature of approximately 2000 K. The pressure isobtained directly from the early time x-ray data, whereas the additional information from the x-ray line widthand intensity at longer times inform a model of crystal nucleation and growth.
