物構研談話会

日時: 2012-11-21 16:30 - 17:30
場所: MLF 第一会議室(東海)/4号館2階輪講室1
会議名: 物構研談話会(12-28)Investigation of deformation twinning in Mg alloys; combined in situ neutron diffraction and acoustic emission 
連絡先: 中尾裕則4868
講演者: Ondrej Muransky博士  (ANSTO)
アブストラクト: The in situ neutron diffraction and in situ acoustic emission
were used in a single in situ experiment in order to study deformation
twinning in two ZM20 Mg alloys with significantly different grain sizes
at room temperature. The combination of these two techniques enables the
distinction between twin nucleation and twin growth. It is shown, that
yielding and immediate post-yielding plasticity in compression along the
extrusion direction is governed primarily by twin nucleation, whereas
the plasticity at higher strains is governed by twin growth and
dislocation slip. It is further shown that the collaborative twin
nucleation dominates yielding in the fine-grained alloy whereas twin
nucleation in the coarse-grained alloy is rather progressive and is
happing over a larger strain range. Additionally, it is shown that
despite the increasing stress required for twinning with the decreasing
grain size, roughly the same overall volume fraction of twins is formed
in the fine and coarse parent grains. This confirms the difficultness of
the alternative deformation modes and it shows a very limited
suppressing effect of grain size on twinning in the case of strongly
textured fine-grained Mg alloy.

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