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

Published version
Peer-reviewed

Type

Article

Change log

Authors

Chen, Y 
Gou, B 
Fu, W 
Chen, C 

Abstract

jats:pIntermittent 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.</jats:p>

Description

Keywords

40 Engineering

Journal Title

Applied Physics Letters

Conference Name

Journal ISSN

0003-6951
1077-3118

Volume Title

117

Publisher

AIP Publishing

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (EP/P024904/1)