Anomalous evolution of microstructure and crystallographic texture during indentation
Anomalous evolution of microstructure and crystallographic texture during indentation
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DOI：
10.1016/j.actamat.2015.12.028
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发表时间：
2016-02
期刊：
影响因子：
9.4
通讯作者：
S. Basu;Zhiyu Wang;C. Saldana
中科院分区：
文献类型：
--
作者：
S. Basu;Zhiyu Wang;C. Saldana
结合取向成像显微镜（OIM）和粘塑性自洽框架数值模拟方法，研究了铜压痕过程中微观组织和晶体织构的演化规律。有人认为，异常的微观结构演变特征，包括加速晶粒破碎和细化导致在低等效应变的区域内靠近压头的界面内的超细晶粒。在细化的加速源被发现在增强的局部晶体学旋转速率表现通过微尺度的应变路径的变化，导致进入界面附近的区域的路径线。这些应变路径的变化被证明是由于跨机械硬/软的微区普遍在铜的变形，尽管没有一个更硬的第二相的异质住宿。利用泰勒因子分析，将变形场的原位表征与OIM耦合，识别微区。除了加速细化，区域附近的接口的压头也表现出立方体纹理，而不是剪切型纹理的其他地方的标本，确认迄今为止未知的异质性的变形力学的几何形状施加在压痕。
The present work combines orientation imaging microscopy (OIM) and visco-plastic self-consistent framework based numerical simulation to study evolution of microstructure and crystallographic texture during indentation of copper. It was seen that anomalous microstructure evolution characteristics involving accelerated grain fragmentation and refinement resulted in ultra-fine grains at low equivalent strains within a zone close to the interface of the indenter. Sources of acceleration in refinement were found in enhanced local crystallographic rotation rates manifesting through micro-scale strain-path changes in pathlines leading into the zone near the interface. These strain path changes were shown to result from heterogeneous accommodation of deformation across mechanically harder/softer micro-zones prevalent in copper despite absence of a harder second phase. The micro-zones were recognized using Taylor factor analysis by coupling in-situ characterization of deformation fields with OIM. In addition to accelerated refinement, zones near the interface of the indenter also exhibited cube textures as opposed to shear-type textures elsewhere in the specimen, confirming a hitherto unknown heterogeneity in the geometry of deformation mechanics imposed during indentation.