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Article: New insight on acoustoplasticity - Ultrasonic irradiation enhances subgrain formation during deformation

TitleNew insight on acoustoplasticity - Ultrasonic irradiation enhances subgrain formation during deformation
Authors
KeywordsAcoustoplasticity
Dislocation dynamics
Electron backscattering diffraction
Hardness test
Subgrains
Issue Date2011
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/ijplas
Citation
International Journal Of Plasticity, 2011, v. 27 n. 5, p. 788-800 How to Cite?
AbstractMany industrial applications make use of ultrasonic vibration to soften metals. The existing understanding of such an acoustoplastic effect is one in which the ultrasonic irradiation either imposes additional stress waves to augment the quasi-static applied load, or causes heating of the metal, whereas the metal's intrinsic deformation resistance or mechanism is assumed to be unaltered by the ultrasound. In this study, indentation experiments performed on aluminum samples simultaneously excited by ultrasound reveal that the latter intrinsically alters the deformation characteristics of the metal. The deformation microstructures underneath the indents were investigated by a combination of cross-sectional microscopic techniques involving focused-ion-beam milling, transmission electron microscopy and crystal orientation mapping by electron backscattered diffraction. The softening effect of the ultrasound is found to constitute recovery associated with extensive enhancement of subgrain formation during deformation. By comparing the microstructures of samples deformed with and without simultaneous application of ultrasound, and those subsequently excited by ultrasound after deformation, the enhanced subgrain formation is proved to be one due to the combined application of the quasi-static loading and the ultrasound, but not a simple addition of the two. Similarly, by comparing with samples deformed while being simultaneously or subsequently heated up, the enhanced subgrain formation by the ultrasound is proved to be a lot greater than that due to the heat that it generates within the metal. Such effects of the ultrasound are interpreted by its ability to enhance dipole annihilation. The superimposed ultrasound causes dislocations to travel longer distances in a jerky manner, so that they can continuously explore until dipole annihilation. © 2010 Elsevier Ltd. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/134414
ISSN
2015 Impact Factor: 5.623
2015 SCImago Journal Rankings: 4.694
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants CouncilHKU7156/08E
University Grants Committee of the Hong Kong Special Administration Region, PR ChinaSEG-HKU06
Croucher Foundation
Funding Information:

The work described in this paper was supported by grants from the Research Grants Council (Project No. HKU7156/08E), as well as from the University Grants Committee (Project No. SEG-HKU06) of the Hong Kong Special Administration Region, PR China. A.H.W.N. would like to acknowledge support in the form of a Senior Research Fellowship from the Croucher Foundation.

References

 

DC FieldValueLanguage
dc.contributor.authorSiu, KWen_HK
dc.contributor.authorNgan, AHWen_HK
dc.contributor.authorJones, IPen_HK
dc.date.accessioned2011-06-17T09:20:09Z-
dc.date.available2011-06-17T09:20:09Z-
dc.date.issued2011en_HK
dc.identifier.citationInternational Journal Of Plasticity, 2011, v. 27 n. 5, p. 788-800en_HK
dc.identifier.issn0749-6419en_HK
dc.identifier.urihttp://hdl.handle.net/10722/134414-
dc.description.abstractMany industrial applications make use of ultrasonic vibration to soften metals. The existing understanding of such an acoustoplastic effect is one in which the ultrasonic irradiation either imposes additional stress waves to augment the quasi-static applied load, or causes heating of the metal, whereas the metal's intrinsic deformation resistance or mechanism is assumed to be unaltered by the ultrasound. In this study, indentation experiments performed on aluminum samples simultaneously excited by ultrasound reveal that the latter intrinsically alters the deformation characteristics of the metal. The deformation microstructures underneath the indents were investigated by a combination of cross-sectional microscopic techniques involving focused-ion-beam milling, transmission electron microscopy and crystal orientation mapping by electron backscattered diffraction. The softening effect of the ultrasound is found to constitute recovery associated with extensive enhancement of subgrain formation during deformation. By comparing the microstructures of samples deformed with and without simultaneous application of ultrasound, and those subsequently excited by ultrasound after deformation, the enhanced subgrain formation is proved to be one due to the combined application of the quasi-static loading and the ultrasound, but not a simple addition of the two. Similarly, by comparing with samples deformed while being simultaneously or subsequently heated up, the enhanced subgrain formation by the ultrasound is proved to be a lot greater than that due to the heat that it generates within the metal. Such effects of the ultrasound are interpreted by its ability to enhance dipole annihilation. The superimposed ultrasound causes dislocations to travel longer distances in a jerky manner, so that they can continuously explore until dipole annihilation. © 2010 Elsevier Ltd. All rights reserved.en_HK
dc.languageengen_US
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/ijplasen_HK
dc.relation.ispartofInternational Journal of Plasticityen_HK
dc.subjectAcoustoplasticityen_HK
dc.subjectDislocation dynamicsen_HK
dc.subjectElectron backscattering diffractionen_HK
dc.subjectHardness testen_HK
dc.subjectSubgrainsen_HK
dc.titleNew insight on acoustoplasticity - Ultrasonic irradiation enhances subgrain formation during deformationen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0749-6419&volume=27&issue=5&spage=788&epage=800&date=2011&atitle=New+insight+on+acoustoplasticity+-+ultrasonic+irradiation+enhances+subgrain+formation+during+deformation-
dc.identifier.emailNgan, AHW:hwngan@hkucc.hku.hken_HK
dc.identifier.authorityNgan, AHW=rp00225en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.ijplas.2010.09.007en_HK
dc.identifier.scopuseid_2-s2.0-79953859161en_HK
dc.identifier.hkuros185619en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-79953859161&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume27en_HK
dc.identifier.issue5en_HK
dc.identifier.spage788en_HK
dc.identifier.epage800en_HK
dc.identifier.isiWOS:000290422800008-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridSiu, KW=37110193600en_HK
dc.identifier.scopusauthoridNgan, AHW=7006827202en_HK
dc.identifier.scopusauthoridJones, IP=34770157200en_HK
dc.identifier.citeulike7923310-

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