Blar i NTNU Open på forfatter "Marioara, Calin Daniel"
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The evolution of precipitates in an Al–Zn–Mg alloy
Thronsen, Elisabeth; Shah, Sohail; Hatzoglou, Constantinos; Marioara, Calin Daniel; Wenner, Sigurd; Andersen, Sigmund Jarle; Holmedal, Bjørn; Holmestad, Randi (Peer reviewed; Journal article, 2023)The precipitation sequence in Al–Zn–Mg alloys has been subject to many revisions over the years as more structural details of the early-stage Guinier-Preston (GP) zones and precipitates have been uncovered. To further ... -
An experimental study on pre-stretched double-chamber 6000-series aluminium profiles subjected to quasi-static and dynamic axial crushing
Qvale, Kristin; Hopperstad, Odd Sture; Reiso, Oddvin; Tundal, Ulf; Marioara, Calin Daniel; Børvik, Tore (Peer reviewed; Journal article, 2020)Automotive crash boxes require a material selection with strength and ductility in a balanced combination. In this work, the behaviour of double-chamber AA6063 and AA6082 aluminium profiles subjected to quasi-static and ... -
Extra electron diffraction spots caused by fine precipitates formed at the early stage of aging in Al-Mg-X (X=Si, Ge, Zn)-Cu alloys
Matsuda, Kenji; Kawai, Akihiro; Watanabe, Katsumi; Seungwon, Lee; Marioara, Calin Daniel; Wenner, Sigurd; Nishimura, Katsuhiko; Matsuzaki, Teiichiro; Nunomura, Norio; Sato, Tatsuo; Holmestad, Randi; Ikeno, Susumu (Journal article; Peer reviewed, 2017)Age-hardenable Al-Mg-Si, Al-Mg-Ge, and Al-Zn-Mg alloys including Cu were investigated by transmission electron microscopy to understand extra diffraction spots that appear in their selected area electron diffraction patterns. ... -
Grain boundary structures and their correlation with intergranular corrosion in an extruded Al-Mg-Si-Cu alloy
Lervik, Adrian; Wenner, Sigurd; Lunder, Otto; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2020)A detailed analysis of grain boundaries in a highly textured Al-Mg-Si-Cu alloy is presented in this work. Electron backscatter diffraction demonstrates the presence of three main categories of grain boundaries in addition ... -
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) ... -
How calcium prevents precipitation hardening in Al–Mg–Si alloys
Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmestad, Randi (Journal article, 2013)We have investigated the effect on precipitate microstructure and hardness upon adding small amounts of Ca to a base Al–Mg–Si alloy. The main investigative techniques were transmission and scanning electron microscopy. We ... -
An improved modelling framework for strength and work hardening of precipitate strengthened Al–Mg–Si alloys
Lu, Feng; Sunde, Jonas Kristoffer; Marioara, Calin Daniel; Holmestad, Randi; Holmedal, Bjørn (Journal article; Peer reviewed, 2022)A modelling framework for the strength and work hardening contributions in age hardened Al–Mg–Si alloys is presented. The modelling work is based on transmission electron microscopy (TEM) measurements of the needle-shaped ... -
Improving ageing kinetics and precipitation hardening in an Al-Mg-Si alloy by minor Cd addition
Qian, Feng; Mørtsell, Eva Anne; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Li, Yanjun (Journal article; Peer reviewed, 2018)This study reports significant improvements in both the age hardening kinetics and peak hardness of an Al-Mg-Si alloy by microalloying with 0.06 at% Cd. A detailed high-angle annular dark-field scanning transmission electron ... -
Influence of low Cu addition on quench sensitivity in Al-Mg-Si alloys
Saito, Takeshi; Marioara, Calin Daniel; Røyset, Jostein; Holmestad, Randi (Journal article, 2014)Quench sensitivity in two Al-Mg-Si alloys, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes, has been investigated using transmission electron microscopy (TEM) and ... -
Influence of natural aging and ramping before artificial aging on the microstructure of two different 6xxx alloys
Hell, Christoph Martin; Søreide, Hanne-Sofie Marie Scisly; Bjørge, Ruben; Marioara, Calin Daniel; Li, Yanjun; Holmestad, Randi (Peer reviewed; Journal article, 2022)In this study the effect of a ramp up to artificial aging (AA) temperature in combination with natural aging (NA) was analyzed for two different industrial aluminium alloys. The alloys differ in their Mg/Si ratio as well ... -
Lattice rotations in precipitate free zones in an Al-Mg-Si alloy
Christiansen, Emil; Marioara, Calin Daniel; Marthinsen, Knut; Hopperstad, Odd Sture; Holmestad, Randi (Journal article; Peer reviewed, 2018)Scanning precession electron diffraction and automated crystal orientation mapping in a transmission electron microscope (TEM) have been applied to quantitatively study the crystal orientation of precipitate free zones ... -
Linking mechanical properties to precipitate microstructure in three Al-Mg-Si(-Cu) alloys
Sunde, Jonas Kristoffer; Lu, Feng; Marioara, Calin Daniel; Holmedal, Bjørn; Holmestad, Randi (Peer reviewed; Journal article, 2021)The mechanical properties of age hardenable Al alloys depend strongly on the precipitate microstructure. This work has investigated the relationship between properties such as strength and ductility and the distribution ... -
Local mechanical properties and precipitation inhomogeneity in large-grained Al–Mg–Si alloy
Hagen, Anette Brocks; Wenner, Sigurd; Bjørge, Ruben; Wan, Di; Marioara, Calin Daniel; Holmestad, Randi; Ringdalen, Inga Gudem (Peer reviewed; Journal article, 2022)Al–Mg–Si (6xxx series) alloys show excellent mechanical properties due to the precipitates formed during heat treatment. However, heat treatment of these alloys results in a soft precipitation free zone (PFZ) close to grain ... -
Mapping the chemistry within, and the strain around, Al-alloy precipitates at atomic resolution by multi-frame scanning transmission electron microscopy
Jones, Lewys; Wenner, Sigurd; Nord, Magnus Kristofer; Ninive, Per Harald; Løvvik, Ole Martin; Marioara, Calin Daniel; Holmestad, Randi; Nellist, Peter (Journal article; Peer reviewed, 2017)Al-Mg-Si(-Cu)alloys, used primarily in the transportation sector, are strengthened by nano-sized precipitate particles. There is a plethora of possible phases, depending onwhich elements are added to the alloy ... -
The microstructural origin of a hardness double-peak in an age-hardened EN-AW 6082
Hell, Christoph Martin; Holmedal, Bjørn; Bjørge, Ruben; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2023)In this study, the origin of a double-peak during artificial aging of an EN-AW 6082 is analyzed with (S)TEM. The acquired TEM data is used as an input into a strength model by Holmedal [1] to explore the origin of the ... -
Modeling over-ageing in Al-Mg-Si alloys by a multi-phase CALPHAD-coupled Kampmann-Wagner Numerical model
Du, Qiang; Tang, Kai; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmedal, Bjørn; Holmestad, Randi (Journal article, 2017)The formation of the equilibrium precipitation phase during ageing treatment of Al-Mg-Si alloys is preceded by a series of metastable phases. Given longer ageing time, higher ageing temperature or elevated temperature ... -
Modeling the Effect of Excess Vacancies on Precipitation and Mechanical Properties of Al–Mg–Si Alloys
Myhr, Ole Runar; Marioara, Calin Daniel; Engler, Olaf (Peer reviewed; Journal article, 2023)A model for vacancy annihilation during aging has been combined with a precipitation model for coupled nucleation, growth, and coarsening in AA 6xxx series aluminum alloys. The simulation results were compared with ... -
Multislice image simulations of sheared needle‐like precipitates in an Al‐Mg‐Si alloy
Christiansen, Emil; Ringdalen, Inga Gudem; Bjørge, Ruben; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2020)The image contrast of sheared needle‐like urn:x-wiley:00222720:media:jmi12901:jmi12901-math-0001 precipitates in the Al‐Mg‐Si alloy system is investigated with respect to shear‐plane positions, the number of shear‐planes, ... -
Muon kinetics in heat treated Al (–Mg)(–Si) alloys
Wenner, Sigurd; Nishimura, Katsuhiko; Matsuda, Kenji; Matsuzaki, Teiichiro; Tomono, Dai; Pratt, Francis L.; Marioara, Calin Daniel; Holmestad, Randi (Journal article, 2013)Al–Mg–Si alloys are heat-treatable and rely on precipitation hardening for their mechanical strength. We have employed the technique of muon spin relaxation to further our understanding of the complex precipitation sequence ... -
Muon Spin Relaxation Study of Solute–Vacancy Interactions During Natural Aging of Al-Mg-Si-Cu Alloys
Wenner, Sigurd; Marioara, Calin Daniel; Nishimura, Katsuhiko; Matsuda, Kenji; Lee, Seungwon; Namiki, Takahiro; Watanabe, Isao; Matsuzaki, Teiichiro; Holmestad, Randi (Journal article; Peer reviewed, 2019)Muon spin relaxation has the unique ability to detect very low concentrations of vacancies and vacancy–solute complexes in solids. In this work, we investigate quaternary Al-Mg-Si-Cu alloys and show that after quenching ...