Browsing SINTEF Open by Author "Holmestad, Randi"
Now showing items 1-20 of 70
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3D modelling of β'' in Al-Mg-Si: towards an atomistic level ab initio based examination of a full precipitate enclosed in a host lattice
Ehlers, Flemming J H; Dumoulin, Stephane; Holmestad, Randi (Peer reviewed; Journal article, 2014)We extend a first principles based hierarchical multi-scale model scheme for describing a fully coherent precipitate in a host lattice to 3D simulations. As our test system, the needle-shaped main hardening Al–Mg–Si alloy ... -
Aberration-corrected HAADF-STEM investigations of precipitate structures in Al-Mg-Si alloys with low Cu additions
Saito, Takeshi; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Lefebvre, Williams; Holmestad, Randi (Peer reviewed; Journal article, 2014)Precipitates in a lean Al–Mg–Si alloy with low Cu addition (~0.10 wt.%) were investigated by aberration-corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Most precipitates were ... -
Atomic structure of solute clusters in Al-Zn-Mg alloys
Lervik, Adrian; Thronsen, Elisabeth; Friis, Jesper; Marioara, Calin Daniel; Wenner, Sigurd; Bendo, Artenis; Matsuda, Kenji; Holmestad, Randi; Andersen, Sigmund Jarle (Peer reviewed; Journal article, 2020)Scanning transmission electron microscopy imaging of Al–Zn–Mg alloys has provided new information on the atomic structures of solute rich clusters forming from a supersaturated solid solution at low temperatures. A unique ... -
Atomic structures of precipitates in Al–Mg–Si alloys with small additions of other elements
Saito, Takeshi; Mørtsell, Eva Anne; Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Friis, Jesper; Matsuda, Kenji; Holmestad, Randi (Peer reviewed; Journal article, 2018)In Al–Mg–Si alloys, additions of only a few weight percent of Mg and Si enable formation of hardening precipitates during heat treatment. The precipitation is complex and is influenced by chemical compositions and ... -
Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy
Wenner, Sigurd; Jones, Lewys; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2017)Scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDS) is a common technique for chemical mapping in thin samples. Obtaining high-resolution elemental maps in the STEM is ... -
Atomic-resolution electron energy loss studies of precipitates in an Al-Mg-Si-Cu-Ag alloy
Wenner, Sigurd; Marioara, Calin Daniel; Ramasse, Quentin; Kepaptsoglou, Despoina Maria; Hage, Fredrik Sydow; Holmestad, Randi (Peer reviewed; Journal article, 2014)Aberration-corrected scanning transmission electron microscopy combined with electron energy loss spectroscopy has been used to determine the distribution of Cu and Ag atomic columns of precipitates in an Al–Mg–Si–Cu–Ag ... -
Atomic-resolution elemental mapping of precipitates in a 7449 aluminium alloy
Wenner, Sigurd; Marioara, Calin Daniel; Lefebvre, Williams; Ramasse, Quentin; Kepaptsoglou, Despoina Maria; Hage, Fredrik Sydow; Holmestad, Randi (Peer reviewed; Journal article, 2014)The high-strength weldable 7xxx series of aluminium alloys are of great importance to the aeronautics industry. Only recently, the complex structures of the AlZnMg hardening precipitates have been solved by HAADFSTEM imaging ... -
Atomistic details of precipitates in lean Al–Mg–Si alloys with trace additions of Ag and Ge studied by HAADF-STEM and DFT
Mørtsell, Eva Anne; Andersen, Sigmund Jarle; Friis, Jesper; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2017)Bonding energies and volume misfits for alloying elements and vacancies in multicomponent Al–Mg–Si alloys have been calculated using density functional theory (DFT). A detailed atomic scale analysis has been done for ... -
AutomAl 6000: Semi-automatic structural labelling of HAADF-STEM images of precipitates in Al–Mg–Si(–Cu) alloys
Tvedt, Haakon; Marioara, Calin Daniel; Thronsen, Elisabeth; Hell, Christoph Martin; Andersen, Sigmund Jarle; Holmestad, Randi (Peer reviewed; Journal article, 2022)When the Al–Mg–Si(–Cu) alloy system is subjected to age hardening, different types of precipitates nucleate depending on the composition and thermomechanical treatment. The main hardening precipitates extend as needles, ... -
Characterisation of structural similarities of precipitates in Mg–Zn and Al–Zn–Mg alloys systems
Bendo, Artenis; Maeda, Tomoyoshi; Matsuda, Kenji; Lervik, Adrian; Holmestad, Randi; Marioara, Calin Daniel; Nishimura, Katsuhiko; Nunomura, Norio; Toda, Hiroyuki; Yamaguchi, Masatake; Ikeda, Ken-ichi; Homma, Tomoyuki (Peer reviewed; Journal article, 2019)High angle annular dark field scanning transmission electron microscopy has been employed to observe precipitate structures in Al–Zn–Mg and Mg–Zn alloys. h1 precipitate structures in Al–Zn–Mg are commonly formed by MgZn2 ... -
Clustering and Vacancy Behavior in High- and Low-Solute Al-Mg-Si Alloys
Wenner, Sigurd; Nishimura, Katsuhiko; Matsuda, Kenji; Matsuzaki, Teiichiro; Tomono, Dai; Pratt, Francis L.; Marioara, Calin Daniel; Holmestad, Randi (Journal article; Peer reviewed, 2014)The precipitate microstructure and vacancy distribution in Al-Mg-Si alloys with different amounts of solute and different heat treatments were investigated by transmission electron microscopy and muon spin relaxation ... -
Comparing intergranular corrosion in Al‐Mg‐Si‐Cu alloys with and without α‐Al(Fe,Mn,Cu)Si particles
Lervik, Adrian; Danbolt, Turid; Furu, Trond; Holmestad, Randi; Lunder, Otto (Peer reviewed; Journal article, 2020)In this study, a model alloy without Fe and Mn additions, is compared with a commercial AA6005 alloy to further understand how the α‐Al(Fe,Mn,Cu)Si particles affect intergranular corrosion (IGC) behaviour. Both alloys were ... -
Compositional and structural properties of pulsed laser-deposited ZnS:Cr films
Nematollahi, Mohammadreza; Yang, Xiaodong; Seim, Eivind; Vullum, Per Erik; Holmestad, Randi; Gibson, Ursula; Reenaas, Turid Worren (Peer reviewed; Journal article, 2016)We present the properties of Cr-doped zinc sulfide (ZnS:Cr) films deposited on Si(100) by pulsed laser deposition. The films are studied for solar cell applications, and to obtain a high absorption, a high Cr content ... -
Copper enrichment on aluminium surfaces after electropolishing and its effect on electron imaging and diffraction
Wenner, Sigurd; Lervik, Adrian; Thronsen, Elisabeth; Marioara, Calin Daniel; Kubowicz, Stephan; Holmestad, Randi (Peer reviewed; Journal article, 2020)Electropolishing is the most common method of preparing samples of aluminium alloys for scanning and transmission electron microscopy, as it yields a good surface quality and large flat, electron-transparent areas. Like ... -
The correlation between intergranular corrosion resistance and copper content in the precipitate microstructure in an AA6005A alloy
Marioara, Calin Daniel; Lervik, Adrian; Grønvold, Julie; Lunder, Otto; Wenner, Sigurd; Furu, Trond; Holmestad, Randi (Peer reviewed; Journal article, 2018)A positive correlation is observed between the amount of Cu incorporated in hardening precipitates and intergranular corrosion resistance in an artificially aged Cu-containing 6005A alloy. Three mechanisms have been ... -
Crystallographic relationships of T-/S-phase aggregates in an Al–Cu–Mg–Ag alloy
Sunde, Jonas Kristoffer; Johnstone, D.N.; Wenner, Sigurd; Van Helvoort, Antonius; Midgley, Paul A.; Holmestad, Randi (Peer reviewed; Journal article, 2018)T-(Al20Cu2Mn3) phase dispersoids are important for limiting recovery and controlling grain growth in Al-Cu alloys. However, these dispersoids can also reduce precipitation hardening by acting as heterogeneous nucleation ... -
Data on atomic structures of precipitates in an Al-Mg-Cu alloy studied by high resolution transmission electron microscopy and first-principles calculations
Chen, Xuanliang; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Friis, Jesper; Lervik, Adrian; Holmestad, Randi; Kobayashi, Equo (Peer reviewed; Journal article, 2021) -
Detailed investigation of the shearing mechanism of β" precipitates in Al-Mg-Si alloys
Christiansen, Emil; Marioara, Calin Daniel; Ringdalen, Inga Gudem; Bjørge, Ruben; Holmedal, Bjørn; Hopperstad, Odd Sture; Holmestad, Randi (Peer reviewed; Journal article, 2020)The mechanism behind shearing of β'' precipitates in Al-Mg-Si alloys during deformation is investigated by applying advanced transmission electron microscopy (TEM) techniques and frozen phonon multislice TEM image simulations ... -
Detecting minute amounts of nitrogen in GaNAs thin films using STEM and CBED
Vatanparast, Maryam; Shao, Yu-Tsun; Rajpalke, Mohana; Fimland, Bjørn-Ove; Reenaas, Turid Dory; Holmestad, Randi; Vullum, Per Erik; Zuo, Jian Min (Peer reviewed; Journal article, 2021)Nitrogen (N) is a common element added to GaAs for band gap engineering and strain compensation. However, detection of small amounts of N is difficult for electron microscopy as well as for other chemical analysis techniques. ... -
Effect of copper addition on the cluster formation behavior of Al-Mg-Si, Al-Zn-Mg, and Al-Mg-Ge in the natural aging
Hatakeyama, Daichi; Nishimura, Katsuhiko; Matsuda, Kenji; Namiki, Takahiro; Lee, Seungwon; Nunomura, Norio; Aida, Tetsuo; Matsuzaki, Teiichiro; Holmestad, Randi; Wenner, Sigurd; Marioara, Calin Daniel (Peer reviewed; Journal article, 2018)The time-dependent resistivity of Al-Mg-Si(-Cu), Al-Zn-Mg(-Cu), and Al-Mg-Ge(-Cu) alloys are studied over a range of constant temperatures between 255 K and 320 K. The resistivity vs time curves for the samples show three ...