In this work, we study the effect of crystallographic orientation and applied triaxiality on the growth of intragranular voids. Two 3D full-field micromechanics methods are used, the dilatational visco-plastic fast-Fourier transform (DVP-FFT) and the crystal plasticity Finite Elements (CP-FE), both of which incorporate a combination of crystalline plasticity and dilatational plasticity. We demonstrate with several select cases that predictions of void growth from both formulations agree qualitatively. With the more computationally efficient DVP-FFT, additional effects of polycrystalline microstructure and the influence of nearest neighborhood are investigated. Crystals bearing a single intracrystalline void are studied in three types of 3D microstructural environments: isolated single crystals, individual equal-sized grains within a regular polycrystal, and individual variable sized grains within a polycrystal with grains and voids randomly located. We show that loading type plays a significant role. In strain-rate controlled conditions, voids in the hardest [111]-crystals grow the fastest in time, whereas in stress-controlled conditions, voids in the softest [100]-crystal grow the fastest in time. The analysis reveals that on average void growth is slower for the same starting orientation in the polycrystal than in the single crystal. We find that at the highest triaxiality tested that the correlation between crystal orientation and void growth rate in the polycrystal strengthens, drawing closer to that seen in the isolated single crystals. These results and model can help guide the microstructural design of polycrystalline materials with high strength and damage-tolerance in high-rate deformation.

在这项工作中，我们研究了晶体取向和应用三轴性对晶内空隙生长的影响。使用了两种 3D 全场微力学方法，即膨胀粘塑性快速傅立叶变换 (DVP-FFT) 和晶体塑性有限元 (CP-FE)，两者都结合了晶体塑性和膨胀塑性。我们通过几个选定的案例证明了两种公式对空隙增长的预测在定性上是一致的。通过计算效率更高的 DVP-FFT，研究了多晶微观结构的额外影响和最近邻域的影响。在三种类型的 3D 微结构环境中研究具有单个晶内空隙的晶体：孤立的单晶、规则多晶中的单个大小相等的晶粒，以及多晶中晶粒和空隙随机分布的单个可变大小的晶粒。我们表明加载类型起着重要作用。在应变率控制条件下，最硬的 [111] 晶体中的空隙随时间增长最快，而在应力控制条件下，最软的 [100] 晶体中的空隙随时间增长最快。分析表明，多晶中相同起始取向的平均空隙生长比单晶中的慢。我们发现在最高三轴度测试中，多晶中晶体取向和空隙生长速率之间的相关性增强，更接近于孤立单晶中所见。