Fine structures of acoustic emission spectra: How to separate dislocation movements and entanglements in 316L stainless steel

Chen, Yan and Gou, Boyuan and Fu, Wei and Chen, Can and Ding, Xiangdong and Sun, Jun and Salje, Ekhard K. H. (2020) Fine structures of acoustic emission spectra: How to separate dislocation movements and entanglements in 316L stainless steel. Applied Physics Letters, 117 (26). p. 262901. ISSN 0003-6951 DOI https://doi.org/10.1063/5.0030508

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Abstract

Intermittent avalanches in a multitude of materials are characterized by acoustic emission, AE, where local events lead to strain relaxations and generate shock waves (so-called “jerks”), which are measured at the sample surface. The bane of this approach is that several avalanche mechanisms may contribute to the same AE spectrum so that a detailed analysis of each individual contribution becomes virtually impossible. It is, hence, essential to develop tools to separate signals from different dynamical processes, such as ferroic domain switching, collapse of porous inclusions, dislocation movements, entanglements, and so on. Particularly, difficult cases are dynamical microstructures in fcc alloys where the AE signal strength is weak. Nevertheless, using profile analysis of AE signals, we can distinguish between two mechanisms, namely, dislocation movements and dynamic entanglements in fcc 316L stainless steel. In this approach, we are able to measure the statistical AE durations of both subsets separately. The fingerprint for superposed avalanches with different durations is seen by the scaling between the energy E and the maximum amplitude A of each avalanche E ∼ Ax with x = 2. While the same exponent x applies for both mechanisms, the scaling relation shows two branches with different absolute energy values. The two mechanisms are then confirmed by separating the energy distributions P(E) ∼ E−ε for the two mechanisms with ε = 1.55 for dislocation movements and ε = 1.36 for entanglements.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA77
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
08 - Green Open Access
Journal or Publication Title: Applied Physics Letters
Volume: 117
Page Range: p. 262901
Identification Number: https://doi.org/10.1063/5.0030508
Depositing User: Sarah Humbert
Date Deposited: 15 Jan 2021 17:57
Last Modified: 21 Jan 2021 02:01
URI: http://eprints.esc.cam.ac.uk/id/eprint/5985

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