物理学报2017，Vol.66Issue(13)：183-193,11.DOI:10.7498/aps.66.136101
基于原位X射线衍射技术的动态晶格响应测量方法研究
Experimental investigation on dynamic lattice resp onse by in-situ Xray diffraction method
摘要
Abstract
Structure evolution under dynamic compression condition (high temperature, high pressure and high strain rate) is one of the most important problems in engineering and applied physics, which is vital for understanding the kinetic mechanism of shock-induced phase transition. In this work, an in-situ dynamic X-ray diffraction (DXRD) diagnostic method is established to probe the lattice response driven by shock waves. The geometry is suitable for the study of laser-shocked crystals. In order to eliminate the measurement error arising from the difference in experimental setup, the static and dynamic lattice diffraction signals are measured simultaneously in one shot by using a nanosecond burst of X-ray emitted from a laser-produced plasma. Experimental details in our investigation are as follows. 1) The laser driven shock wave transit time?tShock and the shock pressure in sample are accurately determined from the shock-wave profile measurement by dual laser heterodyne velocimetry. 2) A laser pump-and-probe technique for adjusting the time-delay of DXRD diagnosis during?tShock, with a series of repeated shock loadings is then employed to generate and measure the dynamic structure evolution. Using this method, the dynamic lattice response of [111] single-crystal iron is studied on Shenguang-II facility. Single-shot diffraction patterns from both unshocked and shocked crystal are successfully obtained. An elastic-plastic transition process—elastic wave followed by a plastic wave—is observed in shocked [111] single-crystal iron on a lattice scale. The lattice compressibility values of the elastic wave and plastic wave are in agreement with those derived from the wave profiles. It is found that the Hugoniot elastic limit is measured to be about 6 GPa under nanosecond-pulsed laser shock compression. Such a high yield strength is consistent with recent laser ramp compression experimental results in polycrystalline Fe [Smith et al. 2011 J. Appl. Phys. 110123515], suggesting that the peak pressure of elastic wave is dependent on the loading rate and the thickness of sample. Based on the analysis of diffraction patterns, the BCC phase is determined to be stable till 23.9 GPa, the highest pressure explored in this work, which might indicate that the phase transition strongly couples with the crystal orientation and loading rate. Some possible physical mechanisms remain to be further studied: whether the transition time hysteresis occurs or the metastable FCC phase exists in shocked [111] single crystal Fe, or the phase transition onset pressure increases under high strain-rate compression. Our DXRD results provide a primary experimental reference for the follow-up study on the phase kinetics.关键词
原位X射线衍射/动态晶格响应/[111]单晶铁Key words
in-situ X-ray diffraction/dynamic lattice response/single crystal iron引用本文复制引用
李俊,谭叶,薛桃,陈小辉,吴强,罗斌强,李牧,阳庆国,陶天炯,金柯,耿华运..基于原位X射线衍射技术的动态晶格响应测量方法研究[J].物理学报,2017,66(13):183-193,11.基金项目
国家自然科学基金 (批准号: 11602251, 11302202)和科学挑战专题(批准号: JCKY2016212A501)资助的课题. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant Nos. 11602251, 11302202) and the Science Challenge Project, China (Grant No. JCKY2016212A501). （批准号: 11602251, 11302202）
