A new geometry of X-ray diffraction survey of single crystal sample in the monochromatic X-ray radiation was developed and applied to obtain a diffraction patterns of shock-compressed NaCl single crystals. This diffraction patterns contain the reflections of different crystal planes and allows to derive both the longitudinal and the transversal strain from the horizontal and vertical shift of the reflections. Compression of the 5-mm -oriented single crystals backed with 0.5-mm graphite window was produced by 6-mm steel impactors accelerated up to velocity 200 - 500 m/sec in 25-mm pneumatic gun. The 30-nsec pulse X-ray source (based on Scandiflash 300 X-ray pulse system) was triggered at the different instances after arrival of the shock wave at the NaCl-window interface. The velocity of the free surface of the graphite window was continuosly monitored by velocity interferometer (VISAR (Barker, L.M., Hollenbach, R.E., J. Appl.Phys, 1974, 45, p.4872-4887)). In the impact experiments performed with the different impact velocities and with the triggering of the X-ray flash at the time instances corresponding to the different states of the NaCl at the plastic wave front no evident transversal strain were found. The material seems to be able to maintain the state of 1-D strain under intensive plastic deformation.
|Title of host publication||American Physical Society, Shock Compression Meeting 1997|
|State||Published - 1 Jul 1997|