Finding and Characterising Active Slip Systems: A Short Review and Tutorial with Automation Tools

Abstract

The behaviour of many materials is strongly influenced by the mechanical properties of hard phases, present either from deliberate introduction for reinforcement or as deleterious precipitates. While it is, therefore, self-evident that these phases should be studied, the ability to do so—particularly their plasticity—is hindered by their small sizes and lack of bulk ductility at room temperature. Many researchers have, therefore, turned to small-scale testing in order to suppress brittle fracture and study the deformation mechanisms of complex crystal structures. To characterise the plasticity of a hard and potentially anisotropic crystal, several steps and different nanomechanical testing techniques are involved, in particular nanoindentation and microcompression. The mechanical data can only be interpreted based on imaging and orientation measurements by electron microscopy. Here, we provide a tutorial to guide the collection, analysis, and interpretation of data on plasticity in hard crystals. We provide code collated in our group to help new researchers to analyse their data efficiently from the start. As part of the tutorial, we show how the slip systems and deformation mechanisms in intermetallics such as the Fe7Mo6 μ-phase are discovered, where the large and complex crystal structure precludes determining a priori even the slip planes in these phases. By comparison with other works in the literature, we also aim to identify “best practises” for researchers throughout to aid in the application of the methods to other materials systems.

Effect of Microstructure on the Cycling Behavior of Li–In Alloy Anodes for Solid-State Batteries

“…These are typically the active slip planes in cubic intermetallics. 23 The interesting insight here is that under high load at the nanoscale, plasticity is observed, with no clear fracture in either the load−displacement data or the indent micrographs. The plasticity seems limited to a single set of slip planes, leading to very clear slip bands.…”

“…An example indent micrograph is shown in Figure S4B, where clear slip bands corresponding to the {1̅01} slip planes, checked using electron backscatter diffraction (EBSD), can be observed. These are typically the active slip planes in cubic intermetallics . The interesting insight here is that under high load at the nanoscale, plasticity is observed, with no clear fracture in either the load–displacement data or the indent micrographs.…”

Characterization Methods along the Process Chain of Electrical Steel Sheet—From Best Practices to Advanced Characterization

“… Exemplary slip trace analysis approaches, ( a ) visual slip trace analysis, ( b ) plane tilt analysis and ( c ) cross-section EBSD. Reprinted with permission from the authors of [ 51 ], © 2021 Creative Commons CC BY 4.0. …”

Quasi-static deformation simulations of molecular crystals

“…Dislocation etch pit techniques 3,4 determine active slip systems using chemical processes. Slip line analysis, 5 is another general method applicable to different classes of materials that can find the active slip system(s) but cannot rank them. This ranking requires specialised experiments such as micropillar compression at pre-set orientations.…”

“…This ranking requires specialised experiments such as micropillar compression at pre-set orientations. 5,6 Electron beams are deleterious to organic molecular crystals; thus, only recently has the scanning electron microscope 7 been used to resolve the orientation map of an organic molecular crystal, a polycrystalline rubrene thin film. Despite such advances, the experimental determination of active slip systems remains challenging, being protracted and expensive; this provides the motivation to try to develop theoretical and computational procedures to find and rank these systems instead.…”