| 1. |
- Baben, Moritz to, et al.
(författare)
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Unprecedented thermal stability of inherently metastable titanium aluminum nitride by point defect engineering
- 2017
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Ingår i: Materials Research Letters. - : TAYLOR & FRANCIS INC. - 2166-3831. ; 5:3, s. 158-169
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Tidskriftsartikel (refereegranskat)abstract
- Extreme cooling rates during physical vapor deposition (PVD) allow growth of metastable phases. However, we propose that reactive PVD processes can be described by a gas-solid paraequilibrium defining chemical composition and thus point defect concentration. Weshow that this notion allows for point defect engineering by controlling deposition conditions. As example we demonstrate that thermal stability of metastable (Ti, Al) Nx, the industrial benchmark coating for wear protection, can be increased from 800 degrees C to unprecedented 1200 degrees C by minimizing the vacancy concentration. The thermodynamic approach formulated here opens a pathway for thermal stability engineering by point defects in reactively deposited thin films.
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| 2. |
- Gemma, Ryota, et al.
(författare)
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The impact of nanoscale compositional variation on the properties of amorphous alloys
- 2020
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The atomic distribution in amorphous FeZr alloys is found to be close to random, nevertheless, the composition can not be viewed as being homogenous at the nm-scale. The spatial variation of the local composition is identified as the root of the unusual magnetic properties in amorphous Fe1-xZrx alloys. The findings are discussed and generalised with respect to the physical properties of amorphous and crystalline materials.
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| 3. |
- Hans, Marcus, et al.
(författare)
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Substrate rotation-induced chemical modulation in Ti-Al-O-N coatings synthesized by cathodic arc in an industrial deposition plant
- 2016
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 305, s. 249-253
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Tidskriftsartikel (refereegranskat)abstract
- Reactive cathodic arc evaporation of Ti-Al-O-N was carried out in an industrial deposition system with two-fold substrate rotation. The structural and compositional evolution of the coatings was studied by combining scanning transmission electron microscopy and 3D atom probe tomography (APT). The formation of alternating O- and N-rich sublayers was identified by APT and can be understood by considering the substrate rotation induced variation in plasma density and fluxes of film-forming species. The effect of plasma density and fluxes on the incorporation of reactive species was studied in stationary deposition experiments and preferred N incorporation occurs, when the growing coating surface is facing the arc source. Thus, the growing surface is positioned in a region of high plasma density characterized by large fluxes of film forming-species. Preferred O incorporation takes place in a region of low plasma density where small fluxes are present, when the growing surface is blocked from the arc source by the substrate holder. Hence, compositional modulations are caused by substrate rotation as the growing coating surface is periodically exposed to regions of high plasma density and large fluxes of film-forming species and regions of low plasma density and small fluxes. These findings are highly relevant for all reactive industrial plasma assisted physical vapor deposition processes utilizing substrate rotation.
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| 4. |
- Hunold, Oliver, et al.
(författare)
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Correlative theoretical and experimental investigation of the formation of AIYB(14) and competing phases
- 2016
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 119:8
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Tidskriftsartikel (refereegranskat)abstract
- The phase formation in the boron-rich section of the Al-Y-B system has been explored by a correlative theoretical and experimental research approach. The structure of coatings deposited via high power pulsed magnetron sputtering from a compound target was studied using elastic recoil detection analysis, electron energy loss spectroscopy spectrum imaging, as well as X-ray and electron diffraction data. The formation of AlYB14 together with the (Y,Al)B-6 impurity phase, containing 1.8 at. % less B than AlYB14, was observed at a growth temperature of 800 degrees C and hence 600 degrees C below the bulk synthesis temperature. Based on quantum mechanical calculations, we infer that minute compositional variations within the film may be responsible for the formation of both icosahedrally bonded AlYB14 and cubic (Y,Al)B-6 phases. These findings are relevant for synthesis attempts of all boron rich icosahedrally bonded compounds with the space group: Imma that form ternary phases at similar compositions.
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| 5. |
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| 6. |
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| 7. |
- Shang, Lin, et al.
(författare)
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Phase formation of Nb2AlC investigated by combinatorial thin film synthesis and ab initio calculations
- 2017
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 37:1, s. 35-41
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Tidskriftsartikel (refereegranskat)abstract
- The phase formation of Nb2AlC was studied by combinatorial thin film synthesis and ab initio calculations. Thin films with lateral chemical composition gradients were synthesized by DC magnetron sputtering at substrate temperatures of 710-870 degrees C. The lowest formation temperature for Nb2AlC is between 710 and 750 degrees C. A predominantly single phase Nb2AlC region where 99% of the X-ray diffraction intensity originate from Nb2AlC was identified. Furthermore, selected area electron diffraction analysis reveals the local formation of single phase Nb2AlC. The limited Al solubility in Nb2AlC compared with Cr2AlC can be understood by comparing the defect formation energy of Al substituting Nb and Cr in Nb2AlC and Cr2AlC, respectively. This methodology may serve as indicator for the magnitude of the A-element homogeneity range in M(n+1)AX(n) phases. The structural and elastic properties of Nb2AlC determined experimentally are in very good agreement with the ab initio calculated data.
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