Synthesis and mechanical testing of grain boundaries at the micro and sub-micro scale

Abstract

The important role of grain boundaries for the mechanical properties of polycrystalline materials has been recognized for many decades. Up to now, the underlying deformation mechanisms at the nano- and micro scale are not understood quantitatively. An overview of the synthesis and subsequent mechanical testing of specific grain boundaries at the micro and sub-micro scale is discussed in the present contribution, including various methods for producing one or multiple specific, crystallographically well-defined grain boundaries. Furthermore, established micromachining methods for isolating and measuring local dislocation-grain boundary interactions are portrayed. Examples of the techniques described are shown with to the aid of copper grain boundaries.

Approaches to Measure the Resistivity of Grain Boundaries in Metals with High Sensitivity and Spatial Resolution: A Case Study Employing Cu

“…Cu bulk bicrystals were grown by the conventional Bridgman method as described in detail in refs ( 9 ) and ( 28 ) using two seed crystals of preselected orientations. In the present case, two [100]-oriented seed crystals were used; one seed crystal was tilted by 36.9° along the [100] axis with respect to the other single crystal seed to form an asymmetric Σ5 tilt grain boundary in refs ( 9 ) and ( 28 ). To obtain a bulk bicrystal, a container of polycrystalline high purity Cu is in contact with the two seed crystals and heated slightly above the melting point.…”

“…Cu bulk bicrystals were grown by the conventional Bridgman method as described in detail in refs and using two seed crystals of preselected orientations. In the present case, two [100]-oriented seed crystals were used; one seed crystal was tilted by 36.9° along the [100] axis with respect to the other single crystal seed to form an asymmetric Σ5 tilt grain boundary in refs and .…”

Size Scaling in Bi-Crystalline Cu Micropillars Containing a Coherent Twin Boundary

“…Slices were next ground, polished, and electrochemically etched using phosphoric acid at 15 V for 45 s to achieve a flat surface without GB grooving as described in Ref. [30] . Cylindrical micropillars were milled using a focused ion beam (FIB, Zeiss Auriga®) workstation in three steps with milling currents ranging from 16 nA to 240 pA.…”