| 1. |
- Almer, J., et al.
(author)
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Strain and texture analysis of coatings using high-energy x-rays
- 2003
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 94:1, s. 697-702
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Journal article (peer-reviewed)abstract
- We investigate the internal strain and crystallographic orientation (texture) in physical-vapor deposited metal nitride coatings of TiN and CrN. A high-energy diffraction technique is presented that uses synchrotron x rays and an area detector, and which allows the strain and intensity distributions of multiple crystallographic planes to be measured by a single x-ray exposure. Unique texture states and nonlinear sin2 strain distributions are observed for all coatings investigated. Quantitative analysis indicates that existing micromechanical models can reasonably predict strain and corresponding stress for mixed-hkl reflections but are inadequate for fully describing measured data. Alternative mechanisms involving deposition-induced defects are proposed
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| 2. |
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| 3. |
- Palmquist, J.-P., et al.
(author)
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Magnetron sputtered W-C films with C60 as carbon source
- 2003
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 444:1-2, s. 29-37
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Journal article (peer-reviewed)abstract
- Thin films in the W–C system were prepared by magnetron sputtering of W with coevaporated C60 as carbon source. Epitaxial deposition of different W–C phases is demonstrated. In addition, nanocrystalline tungsten carbide film growth is also observed. At low C60/W ratios, epitaxial growth of α-W with a solid solution of carbon was obtained on MgO(001) and Al2O3(001) at 400 °C. The carbon content in these films (10–20 at.%) was at least an order of magnitude higher than the maximum equilibrium solubility and gives rise to an extreme hardening effect. Nanoindentation measurements showed that the hardness of these films increased with the carbon content and values as high as 35 GPa were observed. At high C60/W ratios, films of the cubic β-WC1−x (x=0–0.6) phase were deposited with a nanocrystalline microstructure. Films with a grain size <30 Å were obtained and the hardness of these films varied from 14 to 24 GPa. At intermediate C60/W ratios, epitaxial films of hexagonal W2C were deposited on MgO(111) at 400 °C. Polycrystalline phase mixtures were obtained on other substrates and hexagonal WC could be deposited as minority phase at 800 °C.
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| 4. |
- Talyzin, AV, et al.
(author)
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In situ x-ray diffraction study of C-60 polymerization at high pressure and temperature
- 2002
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:16
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Journal article (peer-reviewed)abstract
- The C-60 polymerization was studied by x-ray diffraction in situ in the pressure range 13-18 GPa and at temperatures up to 830 K and nonhydrostatic conditions. Quenched samples were studied ex situ by Raman spectroscopy. The results of the high-pressure and high-temperature treatment are strongly dependent on the history of the sample and stress. An inaccurate increase of the pressure leads to the formation of internal stresses in the sample which gives elliptical Debye-Scherrer diffraction rings already at room temperature. During the subsequent heat treatment a soft amorphous phase is formed. At certain conditions no elliptical diffraction patterns were observed at 13 GPa and 830 K. Samples with a relatively low internal stress showed a transformation to a phase with decreased c-cell parameter compared to the known two-dimensional rhombohedral phase. The observed phase can be described as distorted cubic, but a better fit is achieved using a rhombohedral cell. It is suggested that this phase is a three-dimensional polymer with each C-60 molecule bonded to eight neighbors. This phase showed an increased hardness (about 37 GPa) and a Raman spectrum distinctly different from previously known polymeric phases.
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| 5. |
- Talyzin, A V, et al.
(author)
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Superhard and superelastic films of polymeric C60
- 2001
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In: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 10:11, s. 2044-2048
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Journal article (peer-reviewed)abstract
- The C60 thin film deposited on steel substrate was transformed by high pressure-high temperature treatment to a superhard and superclastic material. The films were studied by Raman spectroscopy in situ at 20 GPa after heating at 300░C and ex situ after the quenching. The hardness and elastic properties of the high-pressure phases have been characterized with nanoindentation. The hardness of the films were determined to be 0.5 ▒ 0.1 GPa and 61.9 ▒ 9 GPa for unmodified C60 and HPHT treated films, respectively. The hardness of the pressurized film is higher than for cubic BN but lower than hardness values reported for ultrahard fullerite samples prepared from powders. An interesting observation was that the HPHT treated film showed an extreme elastic response with an elastic recovery of approximately 90%. ⌐ 2001 Elsevier Science B.V. All rights reserved.
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