000201814 001__ 201814
000201814 005__ 20190317000009.0
000201814 0247_ $$2doi$$a10.1016/j.actamat.2014.08.052
000201814 022__ $$a1359-6454
000201814 02470 $$2ISI$$a000345179800042
000201814 037__ $$aARTICLE
000201814 245__ $$aA New Mechanism for Twin Growth in Mg Alloys
000201814 269__ $$a2014
000201814 260__ $$bElsevier$$c2014$$aOxford
000201814 300__ $$a15
000201814 336__ $$aJournal Articles
000201814 520__ $$aTwinning is an important deformation mode in lightweight Mg alloys, but the mechanisms of nucleation and growth of twins and their interactions with solutes remain largely unresolved. Here, a new model for thermally-activated, stress-driven growth of twin boundaries is presented and the role of random and segregated solutes in controlling this growth is studied analytically and using direct molecular dynamics simulations. Twin growth occurs by the thermally-activated nucleation and expansion of twin dislocation loops on a pre-existing twin boundary. Fluctuations in the local concentration of random solutes lowers the energy barrier for this process and thus facilitates twin growth. Segregation of solutes to the twin boundary strongly increases the energy barrier and suppresses twin growth. In random solid solutions at experimental strain rates, the thermally-activated nucleation process is sufficiently fast at low applied stresses so that growth of the twin is controlled by solute strengthening of the nucleated twin loop as it expands across the twin boundary. Annealing of a deformed sample leads to solute segregation and very strong pinning so that further twinning can only be accomplished by nucleation of new twins, consistent with experimental observations. The new mechanism also (i) operates for detwinning and rationalizes complex twin shapes observed in experiments and (ii) suggests a process for dynamic strain aging commonly observed in Mg alloys at elevated temperatures.
000201814 6531_ $$atwinning
000201814 6531_ $$aMg alloys
000201814 6531_ $$asolute fluctuation
000201814 6531_ $$asegregation
000201814 6531_ $$astrengthening
000201814 700__ $$0246479$$g222139$$aLuque Gomez, Aitor
000201814 700__ $$aGhazisaeidi, Maryam
000201814 700__ $$0246474$$g211624$$aCurtin, William A.
000201814 773__ $$j81$$tActa Materialia$$q442–456
000201814 8564_ $$uhttps://infoscience.epfl.ch/record/201814/files/A%20New%20Mechanism_Twin%20Growth_Mg%20Alloys_Luque%20Ghazisaeidi%20Curtin_epfl.pdf$$zPreprint$$s1603859$$yPreprint
000201814 8564_ $$uhttps://infoscience.epfl.ch/record/201814/files/PPT_Luque_TwinMgAlloy_24WCMM_main.pdf$$zPresentation of the paper at the 24th International Workshop of Computational Mechanics of Materials.$$s3782458$$yPresentation of the paper at the 24th International Workshop of Computational Mechanics of Materials.
000201814 8564_ $$uhttps://infoscience.epfl.ch/record/201814/files/perspective_view_Mg0Al_300K_110MPa.mov$$zOnly the twin boundary interface is shown. Atoms are colored according to their z coordinate. As the interface migrates, the initial boundary (in blue) is substituted by the final one (in red). Green atoms correspond, in general, to the twin dislocation loop$$s31979985$$yOnly the twin boundary interface is shown. Atoms are colored according to their z coordinate. As the interface migrates, the initial boundary (in blue) is substituted by the final one (in red). Green atoms correspond, in general, to the twin dislocation loop
000201814 8564_ $$uhttps://infoscience.epfl.ch/record/201814/files/side_view_Mg0Al_300K_110MPa.mov$$zDetail view of the interface. Atoms are colored according to the common neighbor analysis: red is hcp, otherwise, non-hcp, and particularly the interface. The migration of the interface can be observed$$s19440518$$yDetail view of the interface. Atoms are colored according to the common neighbor analysis: red is hcp, otherwise, non-hcp, and particularly the interface. The migration of the interface can be observed
000201814 8564_ $$uhttps://infoscience.epfl.ch/record/201814/files/top_view_Mg0Al_300K_110MPa.mov$$zOnly the twin boundary interface is shown. Atoms are colored according to their z coordinate. As the interface migrates, the initial boundary (in blue) is substituted by the final one (in red). Green atoms correspond, in general, to the twin dislocation loop$$s37012533$$yOnly the twin boundary interface is shown. Atoms are colored according to their z coordinate. As the interface migrates, the initial boundary (in blue) is substituted by the final one (in red). Green atoms correspond, in general, to the twin dislocation loop
000201814 909C0 $$xU12614$$0252513$$pLAMMM
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000201814 917Z8 $$x222139
000201814 917Z8 $$x148230
000201814 917Z8 $$x222139
000201814 917Z8 $$x222139
000201814 917Z8 $$x222139
000201814 937__ $$aEPFL-ARTICLE-201814
000201814 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000201814 980__ $$aARTICLE