Blar i NTNU Open på forfatter "Mathiesen, Ragnvald"
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Retrieval of three-dimensional spatial information from fast in situ two-dimensional synchrotron radiography of solidification microstructure evolution
Mirihanage, Wajira; Falch, Ken Vidar; Snigireva, Irina; Snigirev, A; Li, Yanjun; Arnberg, Lars; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2014)In situ synchrotron X-ray radiography of columnar dendritic growth in Al–15 wt.% Cu–9 wt.% Si–0.015 wt.% Sr alloy has been carried out with the temporal and spatial resolutions of 100 ms and 0.65 μm, respectively. ... -
Revealing internal flow behaviour in arc welding and additive manufacturing of metals
Aucott, Lee; Dong, Hongbiao; Mirihanage, Wajira; Atwood, Robert; Kidess, Anton; Gao, Shian; Wen, Shuwen; Marsden, John; Feng, Shuo; Tong, Mingming; Connolley, Thomas; Drakopoulos, Michael; Kleijn, Chris R.; Richardson, Ian M.; Browne, David J.; Mathiesen, Ragnvald; Atkinson, Helen V. (Journal article; Peer reviewed, 2018)Internal flow behaviour during melt-pool-based metal manufacturing remains unclear and hinders progression to process optimisation. In this contribution, we present direct time-resolved imaging of melt pool flow dynamics ... -
Revealing the Heterogeneous Nucleation and Growth Behaviour of Grains in Inoculated Aluminium Alloys During Solidification
Xu, Yijiang; Casari, Daniele; Mathiesen, Ragnvald; Li, Yanjun (Peer reviewed; Journal article, 2019)An in situ X-ray radiographic study on the grain nucleation and grain growth of inoculated Al–10Cu and Al–20Cu alloys during isothermal melt solidification and directional solidification conditions with constant cooling ... -
Revealing the heterogeneous nucleation behavior of equiaxed grains of inoculated Al alloys during directional solidification
Xu, Yijiang; Casari, Daniele; Mathiesen, Ragnvald; Li, Yanjun (Journal article, 2018)An in-situ study on the directional solidification of an inoculated Al-20 wt%Cu alloy under well-controlled constant cooling rates and temperature gradients has been carried out using a microfocus X-radiography set-up. The ... -
Rochelle salt - A structural reinvestigation with improved tools. I. the high-temperature paraelectric phase at 308 - K
Mo, Frode; Mathiesen, Ragnvald; Beukes, Jon Are; Vu, Khanh Minh (Peer reviewed; Journal article, 2015)The crystal structure of the high-temperature paraelectric phase of Rochelle salt (K+·Na+·C4H4O62−·4H2O) at 308 K has been reinvestigated using synchrotron X-ray diffraction with refinement parameters R(int) = 0.0123, final ... -
Soft particles assisted grain refinement and strengthening of an Al-Bi-Zn alloy subjected to ECAP
Jia, Hailong; Bjørge, Ruben; Marthinsen, Knut; Mathiesen, Ragnvald; Li, Yanjun (Journal article; Peer reviewed, 2017)With the aim to improve the strength of potential Pb-free Al-Bi based bearing alloys, an Al-6Bi-8Zn alloy was subjected to equal channel angular pressing (ECAP). To reveal the roles played by the soft Bi particles, an ... -
Structural investigation of Norwegian Lophelia Pertusa: Using X-ray diffraction, X-ray computed tomography and Magnetic resonance imaging techniques
Costa Campino e Silva, Melissa (Master thesis, 2024)Lophelia pertusa er kaldtvannskoraller som finnes i blant annet Trondheimsfjorden. Disse er fascinerende og komplekse skapninger som dessverre lider på grunn av miljøendringer. Lophelia pertusa har blitt studert ved bruk ... -
Three-dimensional study of nodule clustering and heterogeneous strain localization for tailored material properties in ductile iron
Olofsson, Jakob; Salomonsson, Kent; Dahle, Arne K.; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2019)Tailored heterogeneous distributions of microstructural features enable extraordinary material performance in biological and physiological structures such as trees, the aortic arch, human teeth and dinosaur skulls. In ... -
Time Resolved X-ray μCT studies of Multiphase Flow in Porous Systems
Hagen Fagerheim, Mats-Johan (Master thesis, 2023)Røntgen mikro computertomografi har blitt anvendt i et in situ studie av et flerfase strømmings-forsøk best ̊aende av parafin og luft inne i et 3D-printet porøst medium bestående av Epoxy Resin. En serie av 57 sekvensielle ... -
Using EELS to measure the local conductivity in Aluminium
Tveitstøl, Kristian (Master thesis, 2023)De plasmoniske egenskapene til ren aluminium har blitt undersøkt ved hjelp av elektronenergitapsspektroskopi med hensikt til˚a reprodusere den makroskopiske elektriske ledningsevnen til materialet. Dette har blitt gjennomført ... -
Zernike phase contrast in high-energy x-ray transmission microscopy based on refractive optics
Falch, Ken Vidar; Lyubormiskiy, Mikhail; Casari, Daniele; Snigirev, Anatoly; Snigireva, Irina; Detlefs, Carsten; Di Michiel, Marco; Lyatun, Ivan; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2018)The current work represents the first implementation of Zernike phase contrast for compound refractive lens based x-ray microscopy, and also the first successful Zernike phase contrast experiment at photon energies above ... -
α-Mg primary phase formation and dendritic morphology transition in solidification of a Mg-Nd-Gd-Zn-Zr casting alloy
Casari, Daniele; Mirihanage, Wajira; Falch, Ken Vidar; Ringdalen, Inga Gudem; Friis, Jesper; Schmid-Fetzer, Rainer; Zhao, Dongdong; Li, Yanjun; Sillekens, Wim H.; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2016)Microstructure evolution in the commercial Mg-Nd-Gd-Zn-Zr alloy Elektron 21, solidified under nearly isothermal conditions, has been studied via in-situ X-ray radiography. For cooling rates View the MathML source≤0.075 ...