Browsing NTNU Open by Author "Holmestad, Randi"
Now showing items 21-40 of 175
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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 (Journal article; Peer reviewed, 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 (Journal article; Peer reviewed, 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 ... -
Characterisation of tungsten-doped silicon - An intermediate band material candidate from ion implantation and nanosecond pulsed laser melting
Ristola, Markus Joel Benjamin (Master thesis, 2019)En overgang til fornybare energikilder er uunnværlig for å motvirke effektene av global oppvarming, og fotovoltaiske solceller er i ferd med å bli en av de mest anvendte løsningene takket deres stadig synkende kostnader ... -
Characterization and structure of precipitates in 6xxx Aluminium Alloys
Holmestad, Randi; Bjørge, Ruben; Ehlers, Flemming J H; Torsæter, Malin; Marioara, Calin Daniel; Andersen, Sigmund Jarle (Journal article; Peer reviewed, 2012)Solute atom nanoscale precipitates are responsible for the favourable mechanical properties of heat treatable aluminium alloys such as Al-Mg-Si (6xxx). The shape, structure and strengthening properties of age-hardening ... -
Characterization of BaTiO3/La0.7Sr0.3MnO3 Thin Films on SrTiO3(111) Substrates - A Transmission Electron Microscopy Study
Holstad, Theodor Secanell (Master thesis, 2016)In this work, an oxide thin film system was investigated by using transmission electron microscopy (TEM) techniques. It is of great interest to study such systems due to their current applications as well as potential ... -
Characterization of particles from dissolved 5049 aluminum alloys, and the microstructure from billet to extruded and drawn tubes
Ender, Yngve Maximilian (Master thesis, 2019)Hydro sin 5049 aluminiumslegering ekstruderes og trekkes til rør for bruk i hovedsakelig bilindustri, hvor den brukes som for eksempel innløps-/utløpsrør for varmevekslere. For å øke fortjenesten er det nødvendig å ... -
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, 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 ... -
Clustering during Natural Aging and its Effect on Precipitation Hardening in Al-Mg-Si Alloys
Martinsen, Fredrik Aleksander (Master thesis, 2011)The effect of clustering during natural aging of three different Al-Mg-Sialloys with equal Mg/Si-ratios, but different Mg+Si contents have beenstudied through hardness measurements and transmission electron mi-croscopy ... -
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 (Journal article; Peer reviewed, 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 ... -
Controlling Phase Purity and Texture of K0.5Na0.5NbO3 Thin Films by Aqueous Chemical Solution Deposition
Gaukås, Nikolai Helth; Dale, Silje Marie; Ræder, Trygve Magnus; Toresen, Andreas; Holmestad, Randi; Glaum, Julia; Einarsrud, Mari-Ann; Grande, Tor (Journal article; Peer reviewed, 2019)Aqueous chemical solution deposition (CSD) of lead-free ferroelectric K0.5Na0.5NbO3 (KNN) thin films has a great potential for cost-effective and environmentally friendly components in microelectronics. Phase purity of KNN ... -
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, 2021)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 ... -
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 (Journal article; Peer reviewed, 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 ... -
Cu atoms suppress misfit dislocations at the β″/Al interface in Al-Mg-Si alloys
Saito, Takeshi; Ehlers, Flemming J H; Lefebvre, Williams; Hernandez-Maldonado, David; Bjørge, Ruben; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Mørtsell, Eva Anne; Holmestad, Randi (Journal article, 2016)The Cu interactions with the Al–Mg–Si alloy main hardening phase β″ are investigated in atomic scale, by using experimental and simulated high angle annular dark-field scanning transmission electron microscopy techniques ... -
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 (Journal article; Peer reviewed, 2021)The dataset refers to the research article “Precipitation processes and structural evolutions of various GPB zones and two types of S phases in a cold-rolled Al-Mg-Cu alloy” [1]. Transmission electron microscopy (TEM) and ... -
Density Functional Theory Studies of Precipitate Interfaces in Aluminium Alloys, with Focus on Theta'-Al2Cu
Østli, Philip (Master thesis, 2016)The atomic structure of bulk crystal of aluminium and the precipitate phase $\theta^\prime$ connected to age-hardening of Al-Cu alloys have been studied using Density Functional Theory (DFT). The lattice constant of ... -
Design and fabrication of (Cr + N) co-doped TiO2 films with a continuous compositional spread
Lysne, Hogne (Doctoral theses at NTNU;2023:228, Doctoral thesis, 2023)Intermediate band solar cells (IBSCs) have a theoretically conversion efficiency that is approximately 50 % higher than for the solar cell technologies dominating today. IBSCs are based on a new type of materials, where ... -
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 (Journal article; Peer reviewed, 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. ... -
Directionality and column arrangement principles of precipitates in Al-Mg-Si-(Cu) and Al-Mg-Cu linked to line defect in Al
Andersen, Sigmund Jarle; Marioara, Calin Daniel; Friis, Jesper; Bjørge, Ruben; Du, Qiang; Ringdalen, Inga Gudem; Wenner, Sigurd; Mørtsell, Eva Anne; Holmestad, Randi; Saito, Takeshi; Røyset, Jostein; Reiso, Oddvin (Journal article, 2016)In the structures of all metastable precipitates in Al-Mg-Cu and Al-Mg-Si alloys, we find that column surrounding of an element column in the needle/lath direction order according to simple principles. Advanced transmission ...