Browsing NTNU Open by Author "Holmestad, Randi"
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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 (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 ... -
3D TEM characterization of silver implanted silicon for intermediate band solar cells
Lysne, Hogne (Master thesis, 2017)As the need for renewable and sustainable energy sources are growing solar cells are turning into one of the most affordable and widely adopted solutions for renewable electricity production. This is driven by a steady ... -
A hybrid aluminium alloy and its zoo of interacting nano-precipitates
Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Ervik, Martin; Holmestad, Randi (Journal article, 2015)An alloy with aluminium as its base element is heat treated to form a multitude of precipitate phases known from different classes of industrial alloys: Al–Cu(–Mg), Al–Mg–Si–Cu, and Al–Zn–Mg. Nanometer-sized needle-shaped ... -
A Theoretic Study of β'' Misfits and Strain in Al-Mg-Si Alloys - A Cluster-Based Approach Combining Density Functional Theory and Linear Elasticity
Ofstad, Sigurd (Master thesis, 2018)Heat treatable aluminium alloys of the 6xxx series are important for many industrial applications in the modern world. They contain small amounts of the alloying elements magnesium and silicon, which cluster together to ... -
Ab initio based interface modeling for fully coherent precipitates of arbitrary size in Al alloys
Ehlers, Flemming J H; Holmestad, Randi (Journal article, 2013)Multiscale modelling of hardening precipitate interfaces in alloy design This project will develop a new multiscale modelling scheme used to investigate hardening precipitate interfaces in metal alloys. The major aim is ... -
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 (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 ... -
Accurately measured precipitate–matrix misfit in an Al–Mg–Si alloy by electron microscopy
Wenner, Sigurd; Holmestad, Randi (Journal article, 2016)The age-hardenable Al–Mg–Si alloy system is strengthened by needle-shaped coherent β″ phase precipitates. Using distortion-corrected high-resolution scanning transmission electron microscopy images, we measure the considerable ... -
An unreported precipitate orientation relationship in Al-Zn-Mg based alloys
Bendo, Artenis; Matsuda, Kenji; Lervik, Adrian; Tsuru, Tomohito; Nishimura, Katsuhiko; Nunomura, Norio; Holmestad, Randi; Marioara, Calin Daniel; Shimuzu, Kazuyuki; Toda, Hiroyuki; Yamaguchi, Masatake (Journal article; Peer reviewed, 2019)Characterization of precipitates in Al-Zn-Mg alloys, using a combination of electron diffraction, bright field transmission electron microscopy and atomic scale scanning transmission electron microscopy imaging revealed ... -
Atom probe tomography investigations of aging of Al-Zn-Mg(-Cu) alloys during room temperature storage or by cyclic plasticity
Shah, Sohail (Doctoral theses at NTNU;2022:369, Doctoral thesis, 2022)Aluminum alloys containing zinc, magnesium, and copper attain strength by forming nanoparticles during thermal treatments. To generate particles by precipitation, first the alloy has to be heated to about 480°C to dissolve ... -
Atomap - Automated Analysis of Atomic Resolution STEM Images
Nord, Magnus Kristofer; Vullum, Per Erik; MacLaren, I; Tybell, Per Thomas Martin; Holmestad, Randi (Journal article, 2017)Atomic resolution scanning transmission electron microscopy (STEM) data contain a large amount of information about the structure of a crystalline material. Often, this information is hard to extract, due to the large ... -
Atomap: a new software tool for the automated analysis of atomic resolution images using two-dimensional Gaussian fitting
Nord, Magnus Kristofer; Vullum, Per Erik; MacLaren, Ian; Tybell, Per Thomas Martin; Holmestad, Randi (Journal article; Peer reviewed, 2017)Scanning transmission electron microscopy (STEM) data with atomic resolution can contain a large amount of information about the structure of a crystalline material. Often, this information is hard to extract, due to the ... -
Atomic Resolution 3-D Reconstruction of Crystal Grain Boundaries
Brenne, Elise Otterlei (Master thesis, 2018)Grain boundaries are typical crystal defects, which to a large extent determines the macroscopic properties of the material. In order to control these properties and design new materials, detailed knowledge about the atomic ... -
Atomic Structure of Hardening Precipitates in Al-Mg-Si Alloys: Influence of Minor Additions of Cu and Zn
Bartawi, Emad H.; Marioara, Calin Daniel; Shaban, Ghada; hatzoglou, constantinos; Holmestad, Randi; Ambat, Rajan (Peer reviewed; Journal article, 2023)Shifting toward sustainability and low carbon emission necessitates recycling. Aluminum alloys can be recycled from postconsumer scrap with approximately 5% of the energy needed to produce the same amount of primary alloys. ... -
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 (Journal article; Peer reviewed, 2021)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 (Journal article; Peer reviewed, 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 (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 (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 (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 (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 ... -
Atomistic Scale Modelling of Defects in Aluminium Alloys
Frafjord, Jonas (Doctoral theses at NTNU;2020:400, Doctoral thesis, 2020)«Deformasjoner som en ser når metall bøyer seg, er en kollektiv bevegelse av små linjedefekter i atomstrukturen.» Dette sitatet oppsummerer temaet til doktorgradsarbeidet som handler om hvordan atomer i aluminium oppfører ...