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dc.contributor.authorEdwards, Thomas
dc.contributor.authorDi Gioacchino, Fabio
dc.contributor.authorGoodfellow, Amy
dc.contributor.authorMohanty, G
dc.contributor.authorWehrs, J
dc.contributor.authorMichler, J
dc.contributor.authorClegg, William
dc.date.accessioned2018-12-07T00:31:06Z
dc.date.available2018-12-07T00:31:06Z
dc.date.issued2019-01-15
dc.identifier.issn1359-6454
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/286398
dc.description.abstractThe occurrence of plasticity below the macroscopic yield stress during tensile monotonic loading of nearly lamellar Ti-45Al-2Nb-2Mn(at%)-0.8vol% TiB2 at both 25 °C and 700 °C, and in two conditions of lamellar thickness, was measured by digital image correlation strain mapping of a remodelled Au surface speckle pattern. Such initial plasticity, not necessarily related to the presence of common stress concentrators such as hard particles or cracks, could occur at applied stresses as low as 64 % of the general yield stress. For a same applied strain it was more prominent at room temperature, and located as slip and twinning parallel to, and near to or at (respect.) lamellar interfaces of all types in soft modeoriented colonies. These stretched the full colony width and the shear strain was most intense in the centre of the colonies. Further, the most highly operative microbands of plasticity at specimen fracture were not those most active prior to yielding. The strain mapping results from polycrystalline tensile loading were further compared to those from microcompression testing of soft-mode stacks of lamellae milled from single colonies performed at the same temperatures. Combined with post-mortem transmission electron microscopy of the pillars, the initial plasticity by longitudinal dislocation glide was found to locate within 30 – 50 nm of the lamellar interfaces, and not at the interfaces themselves. The highly localised plasticity that precedes high cycle fatigue failure is therefore inherently related to the lamellar structure, which predetermines the locations of plastic strain accumulation, even in a single loading cycle.
dc.description.sponsorshipThe work was supported by the EPSRC / Rolls-Royce Strategic Partnership (EP/M005607/1). T.E.J.E. also acknowledges the kind support of the Worshipful Company of Armourers and Brasiers’ Gauntlet Trust.
dc.publisherElsevier BV
dc.titleDeformation of lamellar γ-TiAl below the general yield stress
dc.typeArticle
prism.endingPage139
prism.publicationDate2019
prism.publicationNameActa Materialia
prism.startingPage122
prism.volume163
dc.identifier.doi10.17863/CAM.31519
rioxxterms.versionofrecord10.1016/j.actamat.2018.09.061
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.licenseref.startdate2019-01-15
dc.contributor.orcidEdwards, Thomas [0000-0002-3089-0062]
dc.contributor.orcidDi Gioacchino, Fabio [0000-0003-2056-1510]
dc.identifier.eissn1873-2453
rioxxterms.typeJournal Article/Review
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/M005607/1)
rioxxterms.freetoread.startdate2019-10-02


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