Crystal plasticity modeling the deformation in nanodomained heterogenous structures
Crystal plasticity modeling the deformation in nanodomained heterogenous structures
复制标题
DOI：
10.1557/jmr.2019.63
复制
发表时间：
2019-03
影响因子：
2.7
通讯作者：
Tianju Chen;Caizhi Zhou
中科院分区：
文献类型：
--
作者：
Tianju Chen;Caizhi Zhou
随机分散的纳米颗粒（ng）嵌入在粗颗粒（cg）中的纳米域非均质结构已经显示出打破强度-延性权衡的令人兴奋的潜力，在不损失延性的情况下提供高强度。本文采用离散晶体塑性有限元（discrete-CPFE）模型和基于位错密度的CPFE模型相结合的方法，研究了晶粒尺寸、纳米颗粒体积分数对纳米畴材料强度和变形的影响。我们的分析表明，纳米畴样品的总体流动应力等于或高于混合规律预测的强度。更小的纳米颗粒或更高的纳米颗粒体积分数可以使纳米畴样品更强，因为它们可以更有效地促进纳米颗粒内部的位错积累，并最终提高塑性流动过程中每个滑移系统的临界分解剪应力。由于位错运动受限，ngg周围区域储存了较高的位错密度和较小的塑性应变。此外，嵌入石墨烯的纳米颗粒可以有效地降低纳米畴样品的强度各向异性。
Nanodomained heterogenous structures characterized by randomly dispersed nanograins (NGs) embedded in the coarser grains (CGs) have demonstrated an exciting potential to break the strength–ductility trade-off, providing high strength without the loss of ductility. Here, using a combination of discrete crystal plasticity finite element (discrete-CPFE) model and dislocation density-based CPFE model, we study the effects of grain size, volume fraction of nanograins on the strength and deformation in nanodomained materials. Our analysis shows that the overall flow stresses of nanodomained samples are equal or higher than the strengths predicted by rule of mixtures. Smaller NGs or higher volume fraction of NGs can make the nanodomained samples stronger, as they can be more effective to promote the dislocation accumulations inside the CGs and eventually raise the critical resolved shear stress for each slip system during the plastic flow. Areas surrounding NGs stored higher dislocation densities and less plastic strain, due to the restricted dislocation motion. Furthermore, NGs grain embedded in the CGs can effectively reduce the anisotropy of strength in the nanodomained samples.