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| Main Authors: | , , , , , |
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| Format: | Preprint |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2411.12624 |
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| _version_ | 1866909395780108288 |
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| author | Zhang, Yinxia Bartosik, Matthias Brinckmann, Steffen Bansal, Ujjval Lee, Subin Kirchlechner, Christoph |
| author_facet | Zhang, Yinxia Bartosik, Matthias Brinckmann, Steffen Bansal, Ujjval Lee, Subin Kirchlechner, Christoph |
| contents | The effect of columnar grain boundaries on the fracture toughness was investigated using micro-cantilever fracture testing with a bridge notch, and a unique hard coating consisting of two distinct microstructures: one with columnar grains and another with an epitaxial layer. The bridge-failure sequence qualitatively demonstrated the lower fracture toughness at the columnar-grained structure. Quantitatively, the load drops measured at bridge-failure also revealed a significant decrease in fracture toughness due to grain boundaries. Specifically, the fracture toughness decreased by around 30%, from 4.1 +/- 0.4 MPa m1/2 for epitaxial microstructure to 3.0 +/- 0.3 MPa m1/2 for columnar-grained structure. The fracture toughness of columnar-grained structure is 3.0 +/- 0.2 MPa m1/2 perpendicular to the growth direction higher than 2.7 +/- 0.1 MPa m1/2 along it. These findings suggest that future optimization of hard coatings should focus on grain boundary toughening, and the present toolbox proposes suitable techniques for such microstructure optimization. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_12624 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Columnar grain boundaries are the weakest link in hard coatings: Insights from micro-cantilever testing with bridge notches Zhang, Yinxia Bartosik, Matthias Brinckmann, Steffen Bansal, Ujjval Lee, Subin Kirchlechner, Christoph Applied Physics Materials Science The effect of columnar grain boundaries on the fracture toughness was investigated using micro-cantilever fracture testing with a bridge notch, and a unique hard coating consisting of two distinct microstructures: one with columnar grains and another with an epitaxial layer. The bridge-failure sequence qualitatively demonstrated the lower fracture toughness at the columnar-grained structure. Quantitatively, the load drops measured at bridge-failure also revealed a significant decrease in fracture toughness due to grain boundaries. Specifically, the fracture toughness decreased by around 30%, from 4.1 +/- 0.4 MPa m1/2 for epitaxial microstructure to 3.0 +/- 0.3 MPa m1/2 for columnar-grained structure. The fracture toughness of columnar-grained structure is 3.0 +/- 0.2 MPa m1/2 perpendicular to the growth direction higher than 2.7 +/- 0.1 MPa m1/2 along it. These findings suggest that future optimization of hard coatings should focus on grain boundary toughening, and the present toolbox proposes suitable techniques for such microstructure optimization. |
| title | Columnar grain boundaries are the weakest link in hard coatings: Insights from micro-cantilever testing with bridge notches |
| topic | Applied Physics Materials Science |
| url | https://arxiv.org/abs/2411.12624 |