Spallation is a typical dynamic fracture mode under shock loading and has attracted the attention of most researchers. However, due to the difficulty in measuring temperature in dynamic experiments, the effect of initial temperature on spalling response has been rarely investigated. Molecular dynamics simulation perfectly corresponds to the short duration and high strain rate of the spalling process. Therefore, in this work, molecular dynamics simulations are used to study the spalling reaction of single-crystal aluminum at different initial temperatures. The research has shown that the evolution of spallation is related to dislocation and hole nucleation. First, the spall strength of the material decreases as initial temperature increases, while the dislocation density gradually increases. However, when the initial temperature increases to 750 K, the dislocation density decreases. Then, the number of holes and the degree of damage change as initial temperature increases. However, at the low impact strength (v < 2.0 km/s), the changes in the number of holes and the degree of damage are highly dependent on the initial temperature. In the case of high impact strength, the opposite is true. Finally, the thermodynamic path of the material during impact compression is studied. It is found that melting may occur during compression, release or tension, and damage stages, depending on the initial temperature and impact strength. The discovery and research of these systems have laid a solid foundation for subsequent studies.

With the need of developing new materials, exploring new phenomenon, and discovering new mechanisms under extreme conditions, the response of materials to high-pressure compression attract more attention. However, the high-pressure state deviating from the Hugoniot line is difficult to realize by conventional experiments. Gas gun launching graded materials could reach the state. In our work, the corresponding Al-Cu composites and graded materials are prepared by tape casting and hot-pressing sintering. The microstructure and the acoustic impedance of the corresponding Al-Cu composites are analyzed to explain the impact behavior of Al-Cu graded materials. Computed tomographic testing and three-dimension surface profilometry machine results demonstrated well-graded structure and parallelism of the graded material. Al-Cu GMs with good parallelism are used to impact the Al-LiF target at 2.3 km/s using a two-stage light-gas gun, with an initial shock impact of 20.6 GPa and ramping until 27.2 GPa, deviating from the Hugoniot line.

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In this research, the tensile mechanical properties and microstructure evolution of Cu/Ta nanolayered composites were studied using the molecular dynamics simulation method. By analyzing the tensile stress/strain relationship of Cu/Ta with different interface structures and the movement of dislocations during the stretching process, the deformation mechanism of materials with different interface structures and the effect of interface structures on the tensile strength of Cu/Ta nanolayered composites are revealed. The effect of shear localization during extension is also analyzed. The results show that the dislocation structures at the interfaces of Kurdjumov-Sachs-type and Nishiyama-Wasserman-type samples are parallelogram and triangular interface defect arrays, respectively, which can easily induce two Shockley partial dislocations to slide along different (111) planes, forming an intersection and merging into ladder-rod dislocations. However, dislocations between the Kurdjumov-Sachs š112ć-type sample interfaces exhibit parallel array characteristics, while the interfacial dislocations have non-planar interface components, which can induce deformation twinning. The process is dissociated through a set of intrinsic interfacial dislocations. Shockley partial dislocations are then formed by dislocation motion, creating stacking faults (SF1), and then the second set of partial dislocations may nucleate from the interface and slide on the adjacent SF1 plane, eventually forming deformation twinning.