Columnar grain boundaries are the weakest link in hard coatings: insights from micro-cantilever testing
The effect of columnar grain boundaries (GBs) on the fracture toughness was investigated using micro-cantilever fracture testing in a hard coating featuring two distinct microstructures within a single sample: a columnar-grained top and an epitaxial bottom region. Bridge-notch fracture initiated more readily in the columnar-grained region, indicating reduced toughness. Furthermore, quantitative analysis of the load drops at bridge-failure confirmed a ∼30% decrease in fracture toughness due to GBs: from 4.1 to 3.0 MPa m1/2. These results reveal the detrimental role of GBs in fracture toughness and highlight the importance of microstructural design for improving the mechanical performance of hard coatings.
Authors
- Yinxia Zhang (ORCID: https://orcid.org/0000-0002-5001-4342)
- Subin Lee (ORCID: https://orcid.org/0000-0002-4629-8004)
- M. Bartosik (ORCID: https://orcid.org/0000-0001-5398-4304)
- Ujjval Bansal (ORCID: https://orcid.org/0000-0002-9632-9243)
- Steffen Brinckmann (ORCID: https://orcid.org/0000-0003-0930-082X)
- Christoph Kirchlechner
Institutions
- Karlsruhe Institute of Technology (DE)
- Forschungszentrum Jülich (DE)
- Montanuniversität Leoben (AT)
Publication Details
- Journal
- Materials Research Letters
- Published
- 2025-10-09
- DOI
- https://doi.org/10.1080/21663831.2025.2560526
- Citations
- 1
- Primary Topic
- Metal and Thin Film Mechanics
- Type
- article
- Field-Weighted Citation Impact
- 0.86