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DOI | 10.1126/science.abb2690 |
The heterogeneity of persistent slip band nucleation and evolution in metals at the micrometer scale | |
Steven Lavenstein; Yejun Gu; Dylan Madisetti; Jaafar A. El-Awady | |
2020-10-09 | |
发表期刊 | Science |
出版年 | 2020 |
英文摘要 | Metal fatigues when repeatedly loaded, ultimately failing when cracks form and propagate through the material. Lavenstein et al. studied the origins of this process in nickel. Using high-resolution observations, they tracked how dislocations evolved into microstructural features called persistent slip bands that preceded crack formation. The evolution of tangles of dislocations to a more regularly spaced pattern form the basis for the persistent slip bands and provide a road map for understanding fatigue cracking in metals.
Science , this issue p. [eabb2690][1]
### INTRODUCTION
Metals are the material of choice for many structural applications because they provide the best compromise between strength and ductility. For applications in which cyclic loading is imposed, fatigue failure plagues all metals, and mitigating it is of great importance. In ductile metals, fatigue cracks initiate as small, microstructurally short cracks that gradually grow with increasing number of loading cycles. Although many studies have been dedicated to the crack-growth stage, the transition from a crack-free to a cracked metal remains one of the most challenging topics in the study of fatigue of metal.
The nucleation of microcracks in ductile metals is a consequence of the to-and-fro motion of dislocations during cyclic loading, which leads to dislocation self-organization into long-range ordered structures. Dislocations result from irregularities in the arrangement of atoms in crystalline materials, and their motion leads to plastic deformation. Ladder dislocation structures, more commonly referred to as persistent slip bands (PSBs), are perhaps the most consequential defect structures with regard to fatigue crack initiation. PSBs take the form of regularly spaced, dislocation-dense walls constructed of edge dislocation dipoles with dislocation-sparse channels separating them in a structure resembling a ladder.
### RATIONALE
Our aim is to provide in situ observations and characterization of the formation of PSBs in micrometer-sized Ni single crystals—a representative, model face-centered cubic metal. To do this, we designed a high-frequency microfatigue experiment that replicates the necessary conditions for PSB formation in a very confined material volume. We conducted all experiments in situ in a scanning electron microscope (SEM) on microcrystals having rectangular cross sections with nominal dimensions of 12 μm by 13 μm and gauge lengths of 27 μm. We oriented all microcrystals for single slip, with a fully reversible and symmetric tension-compression cyclic loading imposed along the |
领域 | 气候变化 ; 资源环境 |
URL | 查看原文 |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/298089 |
专题 | 气候变化 资源环境科学 |
推荐引用方式 GB/T 7714 | Steven Lavenstein,Yejun Gu,Dylan Madisetti,et al. The heterogeneity of persistent slip band nucleation and evolution in metals at the micrometer scale[J]. Science,2020. |
APA | Steven Lavenstein,Yejun Gu,Dylan Madisetti,&Jaafar A. El-Awady.(2020).The heterogeneity of persistent slip band nucleation and evolution in metals at the micrometer scale.Science. |
MLA | Steven Lavenstein,et al."The heterogeneity of persistent slip band nucleation and evolution in metals at the micrometer scale".Science (2020). |
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