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- Chien, Yu-Ping, et al.
(författare)
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Deviations between film and target compositions induced by backscattered Ar during sputtering from M-2-Al-C (M = Cr, Zr, and Hf) composite targets
- 2022
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 446
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Tidskriftsartikel (refereegranskat)abstract
- M-Al-C (M = Cr, Zr, and Hf) thin films are deposited from stoichiometric M2AlC composite targets by direct current magnetron sputtering (DCMS) and high power pulsed magnetron sputtering (HPPMS) in an industrial coater. Using DCMS it is observed that the composition of the Cr-Al-C film is close to stoichiometric, while the Al concentration in the Zr-Al-C and Hf-Al-C films is significantly reduced compared to the Al concentration in the targets. It is evident that the magnitude of the difference in Al concentration between the target and the cor-responding film composition is strongly dependent on the atomic mass of the transition metal. Zr and Hf atoms are 1.8 and 3.4 times heavier than Cr. In HPPMS, the target potential is approximately 1.6 times larger than that in DCMS, which can result in the film compositions deviating even stronger from the target composition as compared to DCMS. The Zr-Al-C thin film deposited by HPPMS exhibits a larger Al-deficiency than the film deposited by DCMS. The energy distributions of backscattered Ar neutrals are simulated by utilizing a two-body collision model and the Transport of Ions in Matter (TRIM) code. Based on the simulation results the experimentally observed Al -deficient film compositions can be readily explained: As the mass of the transition metal in the target is increased, both, energy and flux of the (at the target) reflected Ar is increased causing preferential re-sputtering of Al in the films. As stoichiometric compositions are a prerequisite for the formation of single-phase compound thin films it is evident that composite targets with a transition metal mass-dependent Al-overstoichiometry are required to compensate the Al-loss induced by the energetic Ar neutrals.
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| 2. |
- Fekete, Matej, et al.
(författare)
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On the determination of the thermal shock parameter of MAX phases : A combined experimental-computational study
- 2023
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Ingår i: Journal of the European Ceramic Society. - : Elsevier. - 0955-2219 .- 1873-619X. ; 43:13, s. 5484-5492
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Tidskriftsartikel (refereegranskat)abstract
- Thermal shock resistance is one of the performance-defining properties for applications where extreme temperature gradients are required. The thermal shock resistance of a material can be described by means of the thermal shock parameter RT. Here, the thermo-mechanical properties required for the calculation of RT are quantum-mechanically predicted, experimentally determined, and compared for Ti3AlC2 and Cr2AlC MAX phases. The coatings are synthesized utilizing direct current magnetron sputtering without additional heating, followed by vacuum annealing. It is shown that the RT of both Ti3AlC2 and Cr2AlC obtained via simulations are in good agreement with the experimentally obtained ones. Comparing the MAX phase coatings, both experiments and simulations indicate superior thermal shock behavior of Ti3AlC2 compared to Cr2AlC, attributed primarily to the larger linear coefficient of thermal expansion of Cr2AlC. The results presented herein underline the potential of ab initio calculations for predicting the thermal shock behavior of ionically-covalently bonded materials.
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