Mapping hierarchical and heterogeneous micromechanics of a transformative high entropy alloy by nanoindentation and machine learning augmented clustering
Mapping hierarchical and heterogeneous micromechanics of a transformative high entropy alloy by nanoindentation and machine learning augmented clustering
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DOI：
10.1016/j.matdes.2023.111957
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发表时间：
2023-05-04
影响因子：
8.4
通讯作者：
Mishra，Rajiv S.
中科院分区：
文献类型：
--
作者：
Dhal，Abhijeet;Haridas，Ravi Sankar;Mishra，Rajiv S.
传统的宏观力学测试提供了有限的洞察复杂的分级变形行为的变形高熵合金（HEA）。在这项工作中，高吞吐量的微结构-微机械相关的研究，提出了结合高分辨率纳米压痕，网站特定的显微镜，高斯混合模型（GMM）聚类。所研究的HEA具有由奥氏体和马氏体相组成的异质显微组织。弹塑性和微观结构图的比较说明相，晶体取向和界面约束的微观力学响应的依赖性。在马氏体富集区发现的不成比例的高硬度归因于其较高的晶格剪切稳定性，共格孪晶界的创建，以及在纳米压痕过程中在马氏体相中形成的孪晶界面中的丰富的位错活动。孪晶行为的等级取决于加载与h. c. p.马氏体相c轴的相对方向。f.c.c.变形奥氏体晶粒在初始塑性和相变过程中是滑移主导的，并表现出取向依赖性。基于GMM的硬度与模量比的分类直观地将加工硬化与相分布相关联，这是由于奥氏体和马氏体相的独特变形微观力学响应。
Conventional macromechanical tests provide limited insights into complex hierarchical deformation behavior of a transformative high entropy alloy (HEA). In this work, a high throughput microstructure-micromechanical correlative study is presented by combining high-resolution nanoindentation, site-specific microscopy, and Gaussian mixture model (GMM) clustering. The investigated HEA has a heterogenous microstructure consisting of austenite and martensite phases. Comparison of elastoplastic and microstructural maps illustrate dependency of phase, crystal orientation, and interfacial constraints on the micromechanical response. The disproportionately high hardness found in martensite-rich area is attributed to its higher lattice stability to shear, creation of coherent twin boundaries, and copious dislocation activities in the twin interfaces formed in martensite phase during nanoindentation. The hierarchy in twinning behavior depends on the relative direction of loading with the c-axis of h.c.p. martensitic phase. Deformation in f.c.c. austenitic grains is slip-dominated and demonstrates orientation dependency during incipient plasticity and phase transformation. GMM based classification of hardness to modulus ratio intuitively correlates work-hardening with phase distribution due to the distinctive deformation micromechanical responses of austenite and martensite phases.