{"title":"Chemical short-range ordering accompanies shear band initiation in CrCoNi medium entropy alloy","authors":"","doi":"10.1016/j.scriptamat.2024.116381","DOIUrl":null,"url":null,"abstract":"<div><p>Extended X-ray absorption fine structure (EXAFS), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction have been used to monitor the structural development, on atomic-to-nanometer scale, prior to and along with shear band initiation in a face-centered-cubic CrCoNi medium-entropy alloy (MEA) under impact punch shear loads. Our findings provide clear evidence of chemical ordering with accompanying compositional inhomogeneity, on the length scale of one nanometer at the beginning of shear banding initiation. This chemical short-range atomic rearrangement of the three constituent elemental species is a result of atomic diffusion during high-strain-rate straining. The increasing chemical/structural inhomogeneity is likely to exert perturbations to cause uneven energy dissipation and encourage dislocation slip plane softening, both promoting strain localization that may have helped to instigate shear banding. Dynamic recrystallization is observed in later mature shear bands.</p></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":null,"pages":null},"PeriodicalIF":5.3000,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Scripta Materialia","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1359646224004160","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Extended X-ray absorption fine structure (EXAFS), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction have been used to monitor the structural development, on atomic-to-nanometer scale, prior to and along with shear band initiation in a face-centered-cubic CrCoNi medium-entropy alloy (MEA) under impact punch shear loads. Our findings provide clear evidence of chemical ordering with accompanying compositional inhomogeneity, on the length scale of one nanometer at the beginning of shear banding initiation. This chemical short-range atomic rearrangement of the three constituent elemental species is a result of atomic diffusion during high-strain-rate straining. The increasing chemical/structural inhomogeneity is likely to exert perturbations to cause uneven energy dissipation and encourage dislocation slip plane softening, both promoting strain localization that may have helped to instigate shear banding. Dynamic recrystallization is observed in later mature shear bands.
我们利用扩展 X 射线吸收精细结构 (EXAFS)、高分辨率透射电子显微镜 (HRTEM) 和 X 射线衍射来监测面心立方铬钴镍中熵合金 (MEA) 在冲击冲压剪切载荷作用下,剪切带形成之前和形成过程中原子到纳米尺度的结构发展。我们的研究结果提供了明确的证据,证明在剪切带开始形成时,在一纳米的长度范围内存在化学有序性和伴随的成分不均匀性。三种组成元素的化学短程原子重排是高应变速率应变过程中原子扩散的结果。不断增加的化学/结构不均匀性可能会产生扰动,导致能量耗散不均匀,并促使位错滑移面软化,这两种情况都会促进应变局部化,可能有助于引发剪切带。在后期成熟的剪切带中可以观察到动态再结晶。
期刊介绍:
Scripta Materialia is a LETTERS journal of Acta Materialia, providing a forum for the rapid publication of short communications on the relationship between the structure and the properties of inorganic materials. The emphasis is on originality rather than incremental research. Short reports on the development of materials with novel or substantially improved properties are also welcomed. Emphasis is on either the functional or mechanical behavior of metals, ceramics and semiconductors at all length scales.