Abstract Spall dynamic damage has been extensively investigated in ductile metals with weak mechanical anisotropies, such as copper, iron, and aluminum. However, the fracture of stronger anisotropic metals, especially those with HCP structures, remains far less understood. In this work, the void evolution, including nucleation, growth, and coalescence, in single crystal HCP-zirconium at triaxial ultra-strain rates was investigated using molecular dynamics modeling. The internal pressure, microstructural evolution, and void evolution dynamics under various strain rates and temperatures were examined to reveal two competitive mechanisms, i.e., the competition between the dislocation and void evolution and the competition between the structural phase transformation and void evolution. The results showed that at the initial stage of void nucleation, the dislocations and voids exhibited interacted. However, when voids began to grow exponentially, they moved toward the dense dislocation direction and reduced the space for dislocation growth. In addition, the change in the pressure peak was caused by the sequence between the structural phase transformation and void nucleation under the strain rate strengthening effect and temperature softening action. When the void creation was ahead of the structural phase transformation, the pressure dropped once with only one peak. Contrarily, when the void nucleation lagged behind the structural phase transformation, two peaks appeared in the pressure–strain profile. The findings of this study are expected to be useful for the development of a fracture model that accounts for the effects of high strain rates and temperatures on the dynamic damage behavior across multiple scales.

中文翻译：

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考虑高应变率和温度的单晶 HCP-Zr 塑性和基于空隙的动态损伤行为之间的竞争

摘要 在具有弱机械各向异性的延性金属中，如铜、铁和铝，剥落动态损伤得到了广泛的研究。然而，更强的各向异性金属的断裂，尤其是那些具有 HCP 结构的金属，仍然知之甚少。在这项工作中，使用分子动力学模型研究了三轴超应变率下单晶 HCP-锆中的空隙演化，包括成核、生长和聚结。研究了不同应变率和温度下的内压、微观结构演化和空洞演化动力学，揭示了两种竞争机制，即位错和空洞演化之间的竞争以及结构相变和空洞演化之间的竞争。结果表明，在空洞形核初期，显示的位错和空隙相互作用。然而，当空隙开始呈指数增长时，它们向密集位错方向移动，减少了位错增长的空间。此外，压力峰值的变化是由应变速率强化作用和温度软化作用下的结构相变和空隙形核之间的顺序引起的。当空隙产生先于结构相变时，压力下降一次，只有一个峰值。相反，当空隙成核滞后于结构相变时，压力-应变曲线中出现两个峰。