Abstract The defect structures of three different orientation ([001], [011] and [111]) shocked single crystals of tantalum have been characterised using scanning electron microscopy and transmission electron microscopy. The defect evolution and the response of the single crystals are found to be highly dependent on the orientation of the single crystals and the position in the specimen. Crystal plasticity simulation has been used to calculate the strain tensor in the specimens as a function of position and time. The defect types and distributions are analysed in terms of the shock wave and the lateral and back release waves. Twins at the sample centre and front surface were created by the shock wave front. The twins at the back of the sample close to the side surface are produced by the interaction of the release waves. Twinning area fraction and dislocation density are higher at the impact surface region than at the back surface due to decay of the elastic precursor and the difference in loading duration. Twinning acts as a major deformation mechanism and has a strong influence on the Hugoniot elastic limit (HEL) and spall strength when the loading direction is [011] or [111].

中文翻译：

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冲击负载钽单晶的缺陷演变

摘要 用扫描电子显微镜和透射电子显微镜表征了三种不同取向（[001]、[011] 和[111]）冲击的钽单晶的缺陷结构。发现单晶的缺陷演变和响应高度依赖于单晶的取向和样品中的位置。晶体塑性模拟已被用于计算试样中作为位置和时间函数的应变张量。根据冲击波和横向和后向释放波分析缺陷类型和分布。样品中心和前表面的孪晶是由冲击波前产生的。靠近侧面的样品背面的孪晶是由释放波的相互作用产生的。由于弹性前驱体的衰减和加载持续时间的差异，冲击表面区域的孪生面积分数和位错密度高于背面区域。孪生是主要的变形机制，当加载方向为 [011] 或 [111] 时，对 Hugoniot 弹性极限 (HEL) 和剥落强度有很大影响。