| 1. |
- Nygård, K, et al.
(författare)
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Isotope quantum effects in the electron momentum density of water.
- 2007
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 126:15, s. 154508-
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Tidskriftsartikel (refereegranskat)abstract
- The isotope quantum effects in the ground-state electron momentum density of water are studied at temperatures ranging from 5 to 90 degrees C by combining Compton scattering experiments utilizing synchrotron radiation and computational analysis within density functional theory. We observe clear differences in the momentum density between normal and heavy water at room temperature, which are interpreted as predominantly reflecting intramolecular structural differences. The changes in the momentum density upon increasing the temperature are found to be larger for heavy than for normal water, which is attributed primarily to temperature-induced intramolecular structural effects. Both model computations and an ab initio approach qualitatively reproduce the changes in the momentum density as a function of temperature.
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| 2. |
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| 3. |
- Le Lay, G., et al.
(författare)
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STM and synchrotron radiation studies of "prototypical" metal{plus 45 degree rule}semiconductor systems
- 1994
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Ingår i: Surface Science. - 0039-6028. ; 307-309:PART A, s. 280-294
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Tidskriftsartikel (refereegranskat)abstract
- Since the origin of surface science noble metal{plus 45 degree rule}elemental semiconductor couples have been considered as "prototypical" systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the extensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions. © 1994.
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| 4. |
- LELAY, G, et al.
(författare)
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STM AND SYNCHROTRON-RADIATION STUDIES OF PROTOTYPICAL METAL-SEMICONDUCTOR SYSTEMS
- 1994
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 307, s. 280-294
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Tidskriftsartikel (refereegranskat)abstract
- Since the origin of surface science noble metal/elemental semiconductor couples have been considered as ''prototypical'' systems. After three decades of research their structural and electronic properties remain an intriguing maze despite recent advances made, especially thanks to the development of the near-field microscopies and the ''tensive use of synchrotron radiation in surface crystallography and in high-resolution photoelectron spectroscopy. In the last few years, lead, as a replacement inert metal, has nearly gained the pole position in the display of exotic behaviour. This paper gives a flavour of this mystery story and highlights some puzzling questions.
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| 5. |
- Lopez-Crespo, P., et al.
(författare)
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Measuring overload effects during fatigue crack growth in bainitic steel by synchrotron X-ray diffraction
- 2015
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Ingår i: International Journal of Fatigue. - : Elsevier BV. - 1879-3452 .- 0142-1123. ; 71, s. 11-16
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present the results of in situ synchrotron X-ray diffraction measurements of fatigue crack-tip strain fields following a 100% overload (OL) under plane strain conditions. The study is made on a bainitic steel with a high toughness and fine microstructure. This allowed a very high (60 mu m) spatial resolution to be achieved so that fine-scale changes occurring around the crack-tip were captured along the crack plane at the mid-thickness of the specimen. We have followed the crack as it grew through the plastic/residually stressed zone associated with the OL crack location. We observed two effects; one when the enhanced plastic zone is ahead of the crack and one after it has been passed. Regarding the former it was found that the compressive stress at the crack-tip initially falls sharply, presumably due to the increased plastic stretch caused by the OL. This is associated with a concomitant fall in peak tensile stress at K-max, the elastic excursion between K-min and K-max remaining essentially unchanged from before OL. Subsequently discontinuous closure as seen previously for plane stress caused by crack face contact at the OL location limits the elastic strain range experienced by the crack tip and thereby retards crack growth. (C) 2014 Elsevier Ltd. All rights reserved.
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| 6. |
- Lopez-Crespo, P., et al.
(författare)
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Overload effects on fatigue crack-tip fields under plane stress conditions: surface and bulk analysis
- 2013
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Ingår i: Fatigue & Fracture of Engineering Materials & Structures. - : Wiley. - 1460-2695 .- 8756-758X. ; 36:1, s. 75-84
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Tidskriftsartikel (refereegranskat)abstract
- The surface crack opening displacements are characterised by digital image correlation for a (thin) plane stress 316 stainless steel compact tension sample subjected to an overload event. This supports a traditional plasticity-induced closure interpretation showing a knee in the closure response prior to overload, an absence of closure in the accelerated growth regime followed by accentuated closure in the retardation regime. By contrast, measurement of the mid-thickness elastic strain field behind and ahead of the crack made by synchrotron X-ray diffraction shows no evidence of significant crack face contact stresses behind the crack tip on approaching minimum loading. Rather the changes during loading and overloading can mostly be explained by a simple elastic plastic analysis using a value of the yield stress intermediate between the initial yield stress and the UTS. This shows very significant compressive reverse plastic strains ahead of the crack that start to form early during unloading. At the moment it is not clear whether this difference is because of the increasing stress intensity applied as the crack grows, or for some other reason, such as prevention of the crack faces closing mid-thickness due to the reverse plastic zone.
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| 7. |
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| 8. |
- Olsson, C. -O. A., et al.
(författare)
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Strain Profiling of a Ferritic-Martensitic Stainless Steel Sheet - Comparing Synchrotron with Conventional X-Ray Diffraction
- 2015
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Ingår i: Strain. - : Wiley. - 0039-2103. ; 51:1, s. 71-77
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Tidskriftsartikel (refereegranskat)abstract
- To improve the fatigue resistance of stainless steel sheet, it is a common practice to induce compressive residual stress in the surface through shot-peening or tumbling. Stress depth profiles obtained by tumbling of thin stainless steel tensile rods were analysed using laboratory and synchrotron X-Ray Diffraction (XRD). Both the non-destructive synchrotron and the laboratory XRD etch-depth profile gave similar results: a residual stress profile decaying over a depth not exceeding 50 mu m into the material.
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| 9. |
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| 10. |
- Steuwer, Axel, et al.
(författare)
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Evidence of stress-induced hydrogen ordering in zirconium hydrides
- 2009
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Ingår i: Acta Materialia. - : Elsevier BV. - 1873-2453 .- 1359-6454. ; 51:1, s. 145-152
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Tidskriftsartikel (refereegranskat)abstract
- The formation of hydrides in zirconium alloys significantly affects their mechanical properties and is considered to play a critical role in their failure mechanisms, yet relatively little is known about the micromechanical behavior of hydrides in the bulk. This paper presents the result of in situ uniaxial mechanical tensioning experiments on hydrided zircaloy-2 and zircaloy-4 specimens using energy-dispersive synchrotron X-ray diffraction, which suggests that a stress-induced transformation of the delta-hydride to gamma-hydride via ordering of the hydrogen atoms occurs, akin to a Snoek-type relaxation. Subsequent annealing was found to reverse the ordering phenomenon. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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