Self-organized columnar Zr0.7Ta0.3B1.5 core/shell-nanostructure thin films
We recently showed that Zr1−xTaxBy thin films have columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. Layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we determine the atomic-scale nanostructure of sputter...
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Published in | Surface & coatings technology Vol. 401; p. 126237 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Lausanne
Elsevier B.V
15.11.2020
Elsevier BV |
Subjects | |
Online Access | Get full text |
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Summary: | We recently showed that Zr1−xTaxBy thin films have columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. Layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we determine the atomic-scale nanostructure of sputter-deposited columnar Zr0.7Ta0.3B1.5 thin films. The columns, 95 ± 17 Å, are core/shell nanostructures in which 80 ± 15-Å cores are crystalline hexagonal-AlB2-structure Zr-rich stoichiometric Zr1−xTaxB2. The shell structure is a narrow dense, disordered region that is Ta-rich and highly B-deficient. The cores are formed under intense ion mixing via preferential Ta segregation, due to the lower formation enthalpy of TaB2 than ZrB2, in response to the chemical driving force to form a stoichiometric compound. The films with unique combination of nanosized crystalline cores and dense metallic-glass-like shells provide excellent mechanical properties.
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•Zr0.7Ta0.3B1.5 thin films are grown by hybrid high-power impulse and dc magnetron (Ta-HiPIMS/ZrB2-DCMS) co-sputtering.•Zr0.7Ta0.3B1.5 thin films show a self-organized columnar core/shell nanostructure.•Crystalline Zr-rich cores are surrounded by disordered Ta-rich shells.•Unique combination of nanosized-crystalline cores and metallic-glass-like shells provides excellent mechanical properties. |
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ISSN: | 0257-8972 1879-3347 1879-3347 |
DOI: | 10.1016/j.surfcoat.2020.126237 |