• 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 ...
    • Precipitates in aluminium alloys 

      Andersen, Sigmund Jarle; Marioara, Calin Daniel; Friis, Jesper; Wenner, Sigurd; Holmestad, Randi (Journal article; Peer reviewed, 2018)
      Precipitation strengthening is a highly complex phenomenon on the nanoscale, responsible for providing strength in Al-Cu, Al-Mg-Cu, Al-Mg-Zn and Al-Mg-Si alloys. Advances in methodology, especially high-angle annular ...
    • Precipitation in an Al-Mg-Cu alloy and the effect of a low amount of Ag 

      Mihara, Mami; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmestad, Randi; Kobayashi, Equo; Sato, Tatsuo (Journal article, 2016)
      Two high-purity aluminium alloys based on composition Al–3.0Mg–1.0Cu (wt%), one with added 0.4 wt% Ag, were compared up to 11 days ageing at 443 K by means of transmission electron microscopy and hardness measurements. The ...
    • Structural investigation of precipitates with Cu and Zn atomic columns in Al-Mg-Si alloys by aberration-corrected HAADF-STEM 

      Saito, Takeshi; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Lefebvre, Williams; Holmestad, Randi (Journal article; Peer reviewed, 2014)
      Precipitates in Al-Mg-Si alloys with Cu addition (~0.1 wt%) and Zn addition (~1 wt%) were investigated by aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Most ...
    • Structural modifications and electron beam damage in aluminium alloy precipitate θ'-Al2Cu 

      Wenner, Sigurd; Friis, Jesper; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmestad, Randi (Journal article, 2015)
      The –AlCu phase in an Al–4Zn–2Cu–1Mg–0.7Si (wt.%) alloy was investigated by means of scanning transmission electron microscopy. With our specific alloy composition, the phase is often formed with stacking faults on and ...
    • Studying GPI zones in Al-Zn-Mg alloys by 4D-STEM 

      Thronsen, Elisabeth; Frafjord, Jonas; Friis, Jesper; Marioara, Calin Daniel; Wenner, Sigurd; Andersen, Sigmund Jarle; Holmestad, Randi (Journal article; Peer reviewed, 2021)
      A new methodology has been developed to study the fine details of GP zones in age-hardenable aluminium alloys. It is complementary to atomic resolution high-angle annular dark-field scanning transmission electron microscopy ...
    • The effect of Cu and Ge additions on strength and precipitation in a lean 6xxx aluminium alloy 

      Mørtsell, Eva Anne; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Røyset, Jostein; Reiso, Oddvin; Holmestad, Randi (Journal article; Peer reviewed, 2015)
      It has been demonstrated that the strength loss in a lean Al-Mg-Si alloy due to solute reduction could be compensated by back-adding a lower at % of Ge and Cu. Nanosized precipitate needles which are the main cause of ...
    • The Effect of Elastic Strain and Small Plastic Deformation on Tensile Strength of a Lean Al–Mg–Si Alloy 

      Mørtsell, Eva Anne; Westermann, Ida; Marioara, Calin Daniel; Pedersen, Ketill Olav; Andersen, Sigmund Jarle; Røyset, Jostein; Holmedal, Bjørn; Holmestad, Randi (Journal article; Peer reviewed, 2019)
      Al–Mg–Si alloys are usually formed into their final shape by rolling or extrusion. After extrusion, the aluminium profiles are usually straightened, causing the material to be subjected to a small plastic deformation. This ...
    • The effect of heavy deformation on the precipitation in an Al-1.3Cu-1.0Mg-0.4Si wt.% alloy 

      Thronsen, Elisabeth; Marioara, Calin Daniel; Sunde, Jonas Kristoffer; Minakuchi, Kazuhiro; Katsumi, Tetsuya; Erga, Iven; Andersen, Sigmund Jarle; Friis, Jesper; Marthinsen, Knut; Matsuda, Kenji; Holmestad, Randi (Journal article; Peer reviewed, 2020)
      This work has investigated the effect of the combination of natural ageing and 80% pre-deformation after solution heat treatment on precipitation during subsequent artificial ageing in an Al-1.3Cu-1.0Mg-0.4Si wt.% alloy. ...
    • The Effect of Zn on precipitation in Al-Mg-Si alloys 

      Saito, Takeshi; Wenner, Sigurd; Osmundsen, Elisa; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Røyset, Jostein; Lefebvre, Williams; Holmestad, Randi (Journal article, 2014)
      Effects of addition of Zn (up to 1 wt%) on microstructure, precipitate structure and intergranular corrosion (IGC) in an Al–Mg–Si alloys were investigated. During ageing at 185 °C, the alloys showed modest increases in ...
    • The effects and behaviour of Li and Cu alloying agents in lean Al-Mg-Si alloys 

      Mørtsell, Eva Anne; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Ringdalen, Inga Gudem; Friis, Jesper; Wenner, Sigurd; Røyset, Jostein; Reiso, Oddvin; Holmestad, Randi (Journal article, 2016)
      We show how replacing a fraction of Mg with Li in a lean Al-Mg-Si alloy gives comparable strength and enhanced temperature stability. Replacing solute with smaller amounts of Cu and Li also improves thermal stability and ...
    • The Effects of Low Cu Additions and Predeformation on the Precipitation in a 6060 Al-Mg-Si Alloy 

      Saito, Takeshi; Muraishi, Shinji; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Jostein, Røyset; Holmestad, Randi (Journal article, 2013)
      Effects of low Cu additions (≤0.10 wt pct) and 10 pct predeformation before aging on precipitates’ microstructures and types in a 6060 Al-Mg-Si alloy have been investigated using transmission electron microscopy (TEM). It ...
    • The unique hybrid precipitate in a peak-aged Al-Cu-Mg-Ag alloy 

      Gazizov, Marat; Boev, A.O.; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmestad, Randi; Kaibyshev, Rustam; Aksyonov, D.A.; Krasnikov, V.S. (Peer reviewed; Journal article, 2021)
      The prevalent hardening phase forming in an Al-Cu-Mg-Ag alloy after peak-aging at 150 and 190 °C has been investigated using transmission electron microscopy methods. The precipitate atomic structure was determined. It is ...