Columnar grain boundaries are the weakest link in hard coatings: insights from micro-cantilever testing

Yinxia Zhang; Matthias Bartosik; Steffen Brinckmann; Ujival Bansal; Subin Lee; Christoph Kirchlechner

doi:10.1080/21663831.2025.2560526

Columnar grain boundaries are the weakest link in hard coatings: insights from micro-cantilever testing

Yinxia Zhang
, Matthias Bartosik
, Steffen Brinckmann
, Ujival Bansal
, Subin Lee
, Christoph Kirchlechner

Lehrstuhl für Funktionale Werkstoffe und Werkstoffsysteme (425)

Karlsruher Institut für Technologie
Forschungszentrum Jülich GmbH

Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Begutachtung

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.

Originalsprache	Englisch
Seiten (von - bis)	1099-1107
Seitenumfang	9
Fachzeitschrift	Materials Research Letters [Elektronische Ressource]
Jahrgang	2025
Ausgabenummer	Volume 13, Issue 11
DOIs	https://doi.org/10.1080/21663831.2025.2560526
Publikationsstatus	Veröffentlicht - 13 Juli 2025

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10.1080/21663831.2025.2560526

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title = "Columnar grain boundaries are the weakest link in hard coatings: insights from micro-cantilever testing",

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.",

author = "Yinxia Zhang and Matthias Bartosik and Steffen Brinckmann and Ujival Bansal and Subin Lee and Christoph Kirchlechner",

year = "2025",

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Columnar grain boundaries are the weakest link in hard coatings: insights from micro-cantilever testing. / Zhang, Yinxia; Bartosik, Matthias; Brinckmann, Steffen et al.
in: Materials Research Letters [Elektronische Ressource], Jahrgang 2025, Nr. Volume 13, Issue 11, 13.07.2025, S. 1099-1107.

Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Begutachtung

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AU - Bansal, Ujival

AU - Lee, Subin

AU - Kirchlechner, Christoph

PY - 2025/7/13

Y1 - 2025/7/13

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AB - 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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