%0 Journal Article
%A Zhang, Yinxia
%A Bartosik, Matthias
%A Brinckmann, Steffen
%A Bansal, Ujjval
%A Lee, Subin
%A Kirchlechner, Christoph
%T Columnar grain boundaries are the weakest link in hard coatings: insights from micro-cantilever testing
%J Materials Research Letters
%V 13
%N 11
%@ 2166-3831
%C London [u.a.]
%I Taylor & Francis
%M FZJ-2025-04117
%P 1099-1107
%D 2025
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1080/21663831.2025.2560526
%U https://juser.fz-juelich.de/record/1047160