Browsing NTNU Open by Author "Ehlers, Flemming J H"
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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 ... -
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 ... -
Ab initio interface configuration determination for β″ in Al-Mg-Si: Beyond the constraint of a preserved precipitate stoichiometry
Ehlers, Flemming J H (Journal article; Peer reviewed, 2014)The precipitate-host lattice interface configuration stabilities for the β″ phase in the Al–Mg–Si alloy system have been examined using density functional theory. Usually, the supercell based calculations underlying such ... -
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 ... -
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 ... -
HAADF-STEM and DFT investigations of the Zn-containing β'' phase in Al-Mg-Si alloys
Saito, Takeshi; Ehlers, Flemming J H; Lefebvre, Williams; Hernandez-Maldonado, D; Bjørge, Ruben; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmestad, Randi (Journal article, 2014)The Zn-containing β″ phase in Al–Mg–Si alloys was investigated by aberration corrected high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), combined with density functional theory (DFT) ... -
Interface energy determination for the fully coherent β'' phase in Al-Mg-Si: making a case for a first principles based hybrid atomistic modelling scheme
Ehlers, Flemming J H; Dumoulin, Stephane; Marthinsen, Knut; 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 ... -
Interfacial and strain energy analysis from ab initio based hierarchical multi-scale modelling: the Al–Mg–Si alloy β'' phase
Ehlers, Flemming J H; Dumoulin, Stephane; Marthinsen, Knut; Holmestad, Randi (Journal article, 2014)Precipitate-host lattice interface studies have not traditionally been viewed as requiring hybrid model schemes for accurate determination of the interfacial and strain energies. On the other hand, the interfaces of main ... -
Phase stabilization principle and precipitate-host lattice influences for Al-Mg-Si-Cu alloy precipitates
Ehlers, Flemming J H; Wenner, Sigurd; Andersen, Sigmund Jarle; Marioara, Calin Daniel; Lefebvre, Williams; Boothroyd, Chris; Holmestad, Randi (Journal article, 2014)In this work, we seek to elucidate a common stabilization principle for the metastable and equilibrium phases of the Al–Mg–Si–Cu alloy system, through combined experimental and theoretical studies. We examine the structurally ... -
Reversal of the negative natural aging effect in Al-Mg-Si alloys
Martinsen, Fredrik A; Ehlers, Flemming J H; Torsæter, Malin; Holmestad, Randi (Journal article, 2012)The effect of solute clustering on subsequent precipitation has been investigated for three different Al–Mg–Si alloys with similar Mg/Si ratios but different Mg + Si contents. Hardness measurements were carried out (i) ...