Browsing NTNU Open by Author "Mathiesen, Ragnvald"
Now showing items 1-20 of 32
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2D in situ røntgenavbilding av aluminiumskum under kompresjon
Flatøe, Bjørnar Askeland (Master thesis, 2019)Dette studiet ble gjennomført for å bestemme nytteverdien av todimensjonale in situ røntgenavbildninger for å undersøke dynamiske prosesser i tredimensjonale prøver. Aluminium skumble undersøkt ved bruk av radiogram of ... -
Achieving dispersed fine soft Bi particles and grain refinement in a hypermonotectic Al-Bi alloy by severe plastic deformation and annealing
Zha, Min; Yu, Zhiyuan; Qian, Feng; Wang, Huiyuan; Li, Yanjun; Mathiesen, Ragnvald; Roven, Hans Jørgen (Journal article; Peer reviewed, 2018)The present work revealed that equal-channel angular pressing (ECAP) deformation combined with appropriate annealing could represent as an efficient route to modify immiscible as-cast microstructure of a monotectic Al–8Bi ... -
Advanced CT Studies of Deformation Mechanics
Arnestad, Yngve (Master thesis, 2020)I dette prosjektet ble fem ekstruderte aluminiumsstaver utsatt for strekk tester, og derformasjonen analysert med hjelp av røntgentomografi. Strekkstavene hadde 16 hull i et fire ganger fire rutenett drillet gjennom seg ... -
Analytical transmission cross-coefficients for pink beam X-ray microscopy based on compound refractive lenses
Falch, Ken Vidar; Detlefs, Carsten; Snigirev, Anatoly; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2018)Analytical expressions for the transmission cross-coefficients for x-ray microscopes based on compound refractive lenses are derived based on Gaussian approximations of the source shape and energy spectrum. The effects of ... -
Correcting lateral chromatic aberrations in non-monochromatic X-ray microscopy
Falch, Ken Vidar; Detlefs, Carsten; Di Michiel, Marco; Snigireva, Irina; Snigirev, Anatoly; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2016)Lateral chromatic aberration in microscopy based on refractive optics may be reduced significantly by adjustments to the illumination scheme. By taking advantage of a broadened bandwidth illumination, the proposed scheme ... -
Experimental and numerical modelling study on the nucleation and grain growth of inoculated aluminium alloys
Xu, Yijiang (Doctoral theses at NTNU;2017:343, Doctoral thesis, 2017)With the aim to achieve an in-depth understanding on the heterogeneous nucleation and grain growth behavior during solidification of inoculated aluminum alloys, an integrated study by in-situ X-radiography, numerical ... -
Experimental investigation of Gaussian random phase screen model for x-ray diffusers
Falch, Ken Vidar; Detlefs, Carsten; Christensen, Magnus Sebastian; Paganin, David; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2019)The beam diffusing properties of stacked layers of diffuser material were evaluated experimentally and compared to a Gaussian random phase screen model. The model was found to give promising accuracy in combination with a ... -
Faceted interfacial structure of {1011} twins in Ti formed during equal channel angular pressing
Li, Yanjun; Chen, Yongjun; Walmsley, John C.; Mathiesen, Ragnvald; Dumoulin, S; Roven, Hans Jørgen (Journal article; Peer reviewed, 2010)The boundary structure of {1011} deformation twins formed in commercial pure titanium (CP-Ti) during the initial pass ECAP processing has been studied by TEM and HRTEM. A new twining mode with twinning dislocation of b3/3, ... -
Heterogeneous nucleation and grain growth of inoculated aluminium alloys: An integrated study by in-situ X-radiography and numerical modelling
Xu, Yijiang; Casari, Daniele; Du, Qiang; Mathiesen, Ragnvald; Arnberg, Lars; Li, Yanjun (Journal article; Peer reviewed, 2017)A comprehensive study on the heterogeneous nucleation and grain growth of Al-10 wt.%Cu alloys inoculated with Al-5Ti-1B was carried out. To further reveal the solute segregation stifling mechanism, in-situ near-isothermal ... -
High-energy X-ray Transmission Microscopy based on Compound Refractive Lenses
Falch, Ken Vidar (Doctoral theses at NTNU;2017:124, Doctoral thesis, 2017)Summary of thesis: In the results of the work presented in this thesis it has been shown theoretically and demonstrated experimentally that lateral chromatic aberration in hard x-ray transmission microscopy can be ... -
In situ hard X-ray transmission microscopy for material science
Falch, Ken Vidar; Casari, Daniele; Di Michiel, Marco; Detlefs, Carsten; Snigirev, Anatoly; Snigireva, Irina; Honkimäki, Veijo; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2017)Hard X-ray transmission microscopy based on refractive X-ray optics can be employed as a tool in material science to investigate buried-in microstructures in two or three dimensions with spatial resolution approaching 100 ... -
In situ investigation of spinodal decomposition in hypermonotectic Al–Bi and Al–Bi–Zn alloys
Schaffer, Paul; Mathiesen, Ragnvald; Arnberg, Lars; Di Sabatino, Marisa; Snigirev, Anatoly (Journal article; Peer reviewed, 2008)Spinodal decomposition of hypermonotectic Al–6 wt.%Bi, Al–8 wt.%Bi and Al–6 wt.%Bi–8 wt.%Zn alloys has been investigated using synchrotron radiography. In the case of the 6 and 8 wt.%Bi binary alloys undercoolings of ... -
In-situ X-radiographic study of nucleation and growth behaviour of primary silicon particles during solidification of a hypereutectic Al-Si alloy
Xu, Yijiang; Deng, Yun; Casari, Daniele; Mathiesen, Ragnvald; Li, Yanjun (Peer reviewed; Journal article, 2020)Real-time observation of structure evolution in a hypereutectic Al-Si(-Cu) alloy under near-isothermal melt solidification condition was conducted by using in-situ micro-focus X-radiography. The nucleation, growth rate and ... -
In-situ X-ray monitoring of solidification and related processes of metal alloys
Reinhart, G.; Browne, D.J.; Kargl, F.; García-Moreno, F.; Becker, M.; Sondermann, E.; Binder, K.; Mullen, J.S.; Zimmermann, G.; Mathiesen, Ragnvald; Sillekens, W.H.; Nguyen-Thi, H. (Peer reviewed; Journal article, 2023)X-ray radioscopy enables the in-situ monitoring of metal alloy processes and then gives access to crucial information on the dynamics of the underlying phenomena. In the last decade, the utilisation of this powerful imaging ... -
Investigation of `glitches' in the energy spectrum induced by single-crystal diamond compound X-ray refractive lenses
Zhang, Qiuyuan; Polikarpov, Maxim; Klimova, Nataliya; Larsen, Helge Bøvik; Mathiesen, Ragnvald; Emerich, Hermann; Thorkildsen, Gunnar; Snigireva, Irina; Snigirev, Anatoly (Peer reviewed; Journal article, 2018)Single-crystal diamond stands out among all the candidate materials that could be exploited to fabricate compound refractive lenses (CRLs) owing to its extremely stable properties. Among all related experimental features, ... -
Investigation of glitches induced by single-crystal diamond compound refractive lenses based on crystal orientation
Zhang, Qiuyuan; Polikarpov, Maxim; Nataliya, Klimova; Larsen, Helge Bøvik; Mathiesen, Ragnvald; Emerich, Hermann; Thorkildsen, Gunnar; Snigireva, Irina; Snigirev, Anatoly (Journal article; Peer reviewed, 2019)Single-crystal diamond is considered as an ideal material for compound refractive lenses (usually abbreviated to “CRLs”) mainly due to its stability when bathed in strong X-ray radiation. Since CRLs come into operation by ... -
Non-steady 3D dendrite tip growth under diffusive and weakly convective conditions.
Mirihanage, Wajira; Falch, Ken Vidar; Casari, Daniele; McFadden, Shaun; Browne, David J.; Snigireva, I.; Snigirev, Anatoly; Li, Yanjun; Mathiesen, Ragnvald (Journal article; Peer reviewed, 2019)Three dimensional α-Al dendrite tip growth under varying solute gradients in an Al-Cu-Si alloy melt has been studied using real time synchrotron X-ray imaging and mathematical modelling. X-radiographic image sequences with ... -
Prominent role of multi-scale microstructural heterogeneities on superplastic deformation of a high solid solution Al–7Mg alloy
Zha, Min; Zhang, Hongmin; Jia, Hailong; Gao, Yipeng; Jin, Shenbao; Sha, Gang; Bjørge, Ruben; Mathiesen, Ragnvald; Roven, Hans Jørgen; Wang, Hui-Yuan; Li, Yanjun (Peer reviewed; Journal article, 2021)Achieving high superplasticity in single-phase Al alloys remains a challenge, since the fine-grained structure required for superplastic deformation coarsens rapidly in the absence of dispersed second-phase particles during ... -
Quantitative 3D Imaging and Metrology Using Coherent X-ray Scattering
Skjønsfjell, Eirik Torbjørn Bakken (Doctoral theses at NTNU;2017:300, Doctoral thesis, 2017)This thesis has focused on exploring methods of using coherent X-ray scattering at synchrotron sources. New imaging techniques using coherent X-ray scattering have been investigated, and it has been discussed how limitations ... -
Recrystallization and phase transformation of light metals induced by electric current flash heating
Wang, Shubo (Doctoral theses at NTNU;2020:186, Doctoral thesis, 2020)Aluminium (Al), and titanium (Ti) alloys are two commonly used light metal materials in the aerospace and automotive industry due to their high strength-to-weight ratio. Various heat treatments are applied to improve the ...