Mircomechanical insights into unconstrained grain boundary sliding
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arXiv
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| Format: | Preprint |
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2026
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| author | Bandla, Divya Sri Lee, Subin Kirchlechner, Christoph |
| author_facet | Bandla, Divya Sri Lee, Subin Kirchlechner, Christoph |
| contents | Grain boundary sliding (GBS) is a key deformation mechanism at high homologous temperatures in polycrystalline materials, however, its intrinsic behavior is often obscured by additional strain accommodation processes. In this study, dislocation-mediated unconstrained GBS was investigated using Ni bicrystal micropillars containing a single high-angle grain boundary. Micropillar compression tests were conducted over a temperature range from room temperature to $600\,^{\circ}\mathrm{C}$ and strain rates between $5\times10^{-4}$ and $10^{-1}\,\mathrm{s}^{-1}$. By comparing bicrystal and single-crystal responses, the intrinsic contribution of GBS was isolated. The strain-rate sensitivity remained low (SRS $\approx 0.034 \pm 0.017$), comparable to room temperature values, indicating the absence of diffusion-controlled accommodation mechanisms. The activation energy for GBS was determined to be $234\,\mathrm{kJ\,mol^{-1}}$, consistent with grain boundary diffusion-assisted glide of grain boundary dislocations. These results demonstrate that the high strain-rate sensitivity commonly associated with GBS in polycrystals originates primarily from accommodation processes rather than the intrinsic sliding mechanism. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_16026 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Mircomechanical insights into unconstrained grain boundary sliding Bandla, Divya Sri Lee, Subin Kirchlechner, Christoph Materials Science Grain boundary sliding (GBS) is a key deformation mechanism at high homologous temperatures in polycrystalline materials, however, its intrinsic behavior is often obscured by additional strain accommodation processes. In this study, dislocation-mediated unconstrained GBS was investigated using Ni bicrystal micropillars containing a single high-angle grain boundary. Micropillar compression tests were conducted over a temperature range from room temperature to $600\,^{\circ}\mathrm{C}$ and strain rates between $5\times10^{-4}$ and $10^{-1}\,\mathrm{s}^{-1}$. By comparing bicrystal and single-crystal responses, the intrinsic contribution of GBS was isolated. The strain-rate sensitivity remained low (SRS $\approx 0.034 \pm 0.017$), comparable to room temperature values, indicating the absence of diffusion-controlled accommodation mechanisms. The activation energy for GBS was determined to be $234\,\mathrm{kJ\,mol^{-1}}$, consistent with grain boundary diffusion-assisted glide of grain boundary dislocations. These results demonstrate that the high strain-rate sensitivity commonly associated with GBS in polycrystals originates primarily from accommodation processes rather than the intrinsic sliding mechanism. |
| title | Mircomechanical insights into unconstrained grain boundary sliding |
| topic | Materials Science |
| url | https://arxiv.org/abs/2604.16026 |