Slip transfer through coherent Sigma 3 (111) twin boundaries loaded in different crystallographic direction: Insights by Laue microdiffractionTuesday (27.09.2016) 10:45 - 11:00 Part of:
Grain boundaries (GBs) are among the most relevant internal defects which strengthen polycrystalline materials by acting as an obstacle for the dislocation motion. Apart from this, it has been recognized that GB may absorb  and transmit  dislocation. The determining factor in all these phenomena is the grain boundary character which plays a crucial role in the mechanical response. For instance, the well-known high strength of nano?twinned bulk materials is accompanied with surprisingly high ductility . Though the origin of this behavior is still not fully understood, several studies tried to unravel the underlying mechanisms in dislocation?twin-boundary (TB) interaction . However, further investigation are required to thoroughly understand the impact of the TB on the mechanical properties.
The aim of present study is to reveal the dislocation Σ3 TB interaction during uniaxial compression along different crystallographic loading directions. Several micro-pillars with a vertically aligned Σ3(111) TB are fabricated by ion beam micromachining (FIB). The loading axes vary from 〈134〉 to 〈112〉. The samples are tested at BM32 of the ESRF (Grenoble, France) using in situ μLaue diffraction. Mechanical data and post mortem observation show (i) considerable transmission of dislocations through the TB, (ii) little differences between twins and their single crystal counterbodies in terms of yield stress and slip steps and (iii) no measurable differences in dislocation transmission behavior when varying the loading direction.
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