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Micro-mechanical characterization of micro-architectured tungsten coatings

机译:微结构钨涂层的微机械表征

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The current work provides a detailed analysis of the microstructure, mechanical properties, and out-of-plane compression failure modes of tungsten micro-architectured coatings. These coatings are candidates for extremely high temperature applications and for plasma facing components. The current analysis reveals that these coating are multi-layered coatings composed of columnar grains with many pre-existing voids/cracks along grain boundaries. By means of ex situ and in situ microcompression experiments of microcrystals fabricated into these coatings, the mechanical response and possible failure modes have been investigated. These experiments show a size-dependent response in both the flow stress and deformation modes. Smaller microcrystals show a higher strength and large strain burst followed by catastrophic failure dominated by intergranular fracture assisted plastic buckling of the limited number of grains that comprise the microcrystal. Larger microcrystals also show intergranular fracture, however, a continuous hardening response is driven by restricting the lateral movement of the columnar grains by other grains in the crystal. In addition, three-dimensional finite element method simulations were performed to further shed light on the influences of microstructural configurations on the post-yielding behavior, as well as providing a predictive tool of the deformation of these coatings. This work underscores the importance of microstructural design and control of the grain aspect ratio and grain boundary cohesive strength in an effort to extend the life of such micro-architectured coatings.
机译:当前的工作提供了对钨微结构涂层的微观结构,力学性能和面外压缩破坏模式的详细分析。这些涂层是极高温应用和等离子表面组件的候选材料。当前的分析表明,这些涂层是由柱状晶粒组成的多层涂层,这些晶粒沿晶界具有许多预先存在的空隙/裂纹。通过对制成这些涂层的微晶进行异位和原位微压缩实验,研究了其机械响应和可能的破坏模式。这些实验显示了在流动应力和变形模式下尺寸依赖的响应。较小的微晶显示出较高的强度和较大的应变破裂,随后发生灾难性破坏,而破坏性破坏主要由构成微晶的有限数量晶粒的晶间断裂辅助塑性屈曲所致。较大的微晶也显示出晶间断裂,但是,通过用晶体中的其他晶粒限制柱状晶粒的横向运动来驱动连续的硬化反应。此外,还进行了三维有限元方法模拟,以进一步揭示微观结构构型对屈服后性能的影响,并为这些涂层的变形提供预测工具。这项工作强调了微结构设计以及控制晶粒长宽比和晶界粘结强度的重要性,以延长此类微结构涂层的寿命。

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