Journal Article

FZJ-2025-04117

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Columnar grain boundaries are the weakest link in hard coatings: insights from micro-cantilever testing

Zhang, Y. ; Bartosik, M. ; Brinckmann, S.FZJ* ; Bansal, U. ; Lee, S. (Corresponding author) ; Kirchlechner, C.

2025
Taylor & Francis London [u.a.]

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Please use a persistent id in citations: doi:10.1080/21663831.2025.2560526  doi:10.34734/FZJ-2025-04117

Abstract: 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.

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Contributing Institute(s):

1. Werkstoffstruktur und -eigenschaften (IMD-1)

Research Program(s):

1. 1241 - Gas turbines (POF4-124) (POF4-124)

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