| 1. |
- Altenkirch, J., et al.
(author)
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The extent of relaxation of weld residual stresses on cutting out cross-weld test-pieces
- 2009
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In: Powder Diffraction. - : Cambridge University Press (CUP). - 0885-7156 .- 1945-7413. ; 24:2, s. 31-36
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Journal article (peer-reviewed)abstract
- Weld residual stress (RS) measurements are often undertaken on test-pieces which have been Cut Out from large components, yet it remains unclear to what extent the RSs in test-pieces are representative of those present in the original component. Similarly weld mechanical performance tests are frequently undertaken on cross-weld test-pieces without a proper understanding of the level or influence of retained RS. We present a systematic study of the relaxation of longitudinal RS in thin-plate butt welds produced using different materials and welding methods (FSW, laser-MIG, and pulsed-MIG). In each case the RSs were measured repeatedly in the same location as the welds were progressively and symmetrically cut down. Although cutting inevitably leads to stress redistribution, significant relaxation of the longitudinal RS was only observed when the weld length or width was reduced to below a certain value. This critical value appears to correlate with the lateral width of the tensile zone local to the weld-line and may be considered to be the characteristic length as defined in St. Venant's principle. Further, it was found that the level of stress relaxation as a function of weld length for all the welds studied could be collapsed onto a single empirical curve using a simple approach based on the characteristic length scales of the weld. Given the range of materials and welding methods used, this relation appears to be of general use for thin-plate welds although further work is required to test the limits of its applicability. (C) 2009 International Centre for Diffraction Data. [DOI: 10.1154/1.3152580]
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| 2. |
- Borjesson, Jimmy, et al.
(author)
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Medical applications of X-ray fluorescence for trace element research
- 2007
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In: Powder Diffraction. - : Cambridge University Press (CUP). - 0885-7156 .- 1945-7413. ; 22:2, s. 130-137
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Journal article (peer-reviewed)abstract
- Techniques for estimation of element levels directly in humans (noninvasive in vivo) or in samples (in vitro) from humans are reviewed. Toxic, nonessential, trace elements may cause temporary or permanent damage to various organs and tissues in humans. There is thus a need to control the concentrations. Knowledge of the relations between toxic effects and element concentration may be extracted from measurements in humans as well as in samples from humans and her environment. Applications traditionally include occupationally exposed subjects, but an increasing research area is studies of members of the general population and of patients undergoing therapy for malignant and other diseases. Most in vivo XRF studies deal with lead in bone and cadmium in kidneys. For retired lead workers, a clear association has been demonstrated between bone lead and blood lead, due to endogenous lead excretion from the skeleton. A study of mercury in vivo showed that the technique is capable of detecting mercury in heavily exposed worker's kidneys. In vivo XRF in cancer and rheumatology patients has helped to understand how platinum and gold are retained in the human body. The newest in vivo applications include zinc in prostate gland and arsenic in skin. (c) 2007 International Centre for Diffraction Data.
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| 3. |
- Cong, D. Y., et al.
(author)
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Neutron diffraction study on crystal structure and phase transformation in Ni-Mn-Ga ferromagnetic shape memory alloys
- 2007
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In: Powder Diffraction. - : Cambridge University Press (CUP). - 0885-7156 .- 1945-7413. ; 22:4, s. 307-311
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Journal article (peer-reviewed)abstract
- Crystal structure and phase transformation behaviors in two Ni-Mn-Ga ferromagnetic shape memory alloys (FSMAs) with compositions of Ni48Mn30Ga22 and Ni53Mn25Ga22 (at. %) as a function of temperature were investigated by in situ neutron diffraction experiments. Neutron diffraction technique proves to be highly efficient in characterizing structural transformation in Ni-Mn-Ga FSMAs, which consist of nearby elements in the periodic table. Our neutron results show that Ni48Mn30Ga22 has a cubic, L-21 Heusler structure from 373 to 293 K. Its crystal structure changes into a seven-layered orthorhombic martensitic structure when cooled to 243 K, and no further transformation is observed upon cooling to 19 K. Neutron diffraction results also show that Ni53Mn25Ga22 has a tetragonal 14/mmm martensitic structure from 20 to 403 K. A pre-transformation around room temperature is observed from an abrupt jump in unit-cell volume of Ni53Mn25Ga22, which corresponds with an endothermic peak detected in a heated DSC curve.
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| 4. |
- El Hachmi, Abdelhadi, et al.
(author)
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Synthesis and Rietveld refinements of new ceramics Sr2CaFe2WO9 and Sr2PbFe2TeO9 perovskites
- 2018
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In: Powder Diffraction. - : J C P D S-INT CENTRE DIFFRACTION DATA. - 0885-7156 .- 1945-7413. ; 33:2, s. 134-140
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Journal article (peer-reviewed)abstract
- Ceramics of Sr2CaFe2WO9 and Sr2PbFe2TeO9 double perovskites have been prepared in polycrystalline form by solid-state technique, in the air. The crystalline structure was analyzed using X-ray powder diffraction (XRPD) at room temperature. Rietveld analysis of XRPD) patterns show that both compounds adopt a tetragonal structure with space group I4/m, with unit cell parameters a = 5.5453(1) angstrom, c = 7.8389(1) angstrom for Sr(2)CaFc(2)WO(9), and a = 5.5994(15) angstrom, c = 7.8979(30) angstrom for Sr2PbFe2TeO9. A certain degree of anti-site disordering of W and/or Te and Fe on the B -sites have been detected, indicating the presence of a partial amount of W and/or Te at Fe positions and vice versa.
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| 5. |
- Larsson, Mikael, et al.
(author)
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Cu K-edge XANES : polymer, organic, inorganic spectra, and experimental considerations
- 2017
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In: Powder Diffraction. - : Cambridge University Press. - 0885-7156 .- 1945-7413. ; , s. 1-5
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Journal article (peer-reviewed)abstract
- In pursuit of design and characterisation of Cu adsorbing in thin films, we present data from a large variety of Cu-K edge X-ray Absorption Near Edge Spectroscopy (XANES) spectra obtained from organic and inorganic standards. Additionally, we have explored the impact of beam damage inducing redox alterations. Polymer nanoparticles were tested against films to produce higher concentration samples while maintaining high surface area to bulk effects. Spectra from nanoparticles were highly comparable to thin films of ~8 nm thickness, implying comparable contributions by surface effects on copper association. Finally, we observed no impact on Cu XANES spectra from vitrification with dimethyl sulfoxide to produce amorphous frozen, hydrated samples. The spectra should act as a valuable resource in assisting the design of experiments and identification of copper associations.
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| 6. |
- Santisteban, Javier R., et al.
(author)
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Determination of residual stresses around blisters in Zr-2.5%Nb pressure tubes
- 2009
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In: Powder Diffraction. - : Cambridge University Press (CUP). - 0885-7156 .- 1945-7413. ; 24:2, s. 72-76
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Journal article (peer-reviewed)abstract
- We have used synchrotron X-ray diffraction experiments to measure the strain field introduced by a hydride blister grown on a section of a pressure tube from a CANDU nuclear reactor. After charging the tube section with a homogeneous hydrogen concentration of 300 wt ppm, the blister was produced by creating a small cold spot on its surface (similar to 200 degrees C), while the bulk was kept at a temperature of 338 degrees C over a period of 1008 h. The blister studied here is ellipsoidal in shape, with its long axis along the tube axial direction. The experiments were performed on the wiggler beam line ID15 at the European Synchrotron Radiation Facility (ESRF) using a polychromatic beam of high-energy X-rays (60 to 300 keV). Unlike conventional X-ray diffraction, in this mode the scattering angle is fixed and the diffracted beam is discriminated on the basis of the photon energy. The results show that the blister is composed by two crystallographic phases (delta-ZrH and alpha-Zr), with volume fractions varying with position. The maximum stresses appear at the blister-matrix interfaces. Near the tube outer surface, we found large compressive stresses of (-450 +/- 90) MPa along the blister long axis, and tensile stresses (+320 +/- 90) MPa along the tube hoop direction. The main uncertainty in these stresses results from the uncertainty in the elastic constants of the hydride phase. Large strains and broad peaks were observed for this phase, which were explained by a rather low Young's modulus (35 GPa) for the hydride. The results are compared with finite element simulations found in the literature. (C) 2009 International Centre for Diffraction Data. [DOI: 10.1154/1.3139056]
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