• 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 (Peer reviewed; Journal article, 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 ...
    • Effect of cyclic ageing on the early-stage clustering in Al–Zn-Mg(-Cu) alloys 

      Shah, Sohail; Thronsen, Elisabeth; Hatzoglou, Constantinos; Wenner, Sigurd; Marioara, Calin Daniel; Holmestad, Randi; Holmedal, Bjørn (Peer reviewed; Journal article, 2022)
      The cyclic application of mechanical stress to aluminum alloys at room temperature, referred to as cyclic ageing, continuously injects vacancies, enabling dynamic precipitation of a fine distribution of solute clusters. ...
    • 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 (Peer reviewed; Journal article, 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 low Cu additions on precipitate crystal structures in overaged Al-Mg-Si(-Cu) alloys 

      Sunde, Jonas Kristoffer; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2020)
      This study concerns the effect of low Cu additions (<0.1 at.%) on the precipitate crystal structure evolution in three Al-Mg-Si(-Cu) alloys during overageing. The evolution was assessed through a combination of atomic ...
    • Effect of pre-deformation on age-hardening behaviors in an Al-Mg-Cu alloy 

      Chen, Xuanliang; Daehan, Kim; O, Minho; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Lervik, Adrian; Holmestad, Randi; Kobayashi, Equo (Peer reviewed; Journal article, 2021)
      The effects of 3%–50% pre-deformation following solution heat treatment on the age hardening of an Al-3Mg-1Cu alloy have been investigated by Vickers microhardness measurement, tensile tests, differential scanning calorimetry, ...
    • The Effect of Small Additions of Fe and Heavy Deformation on the Precipitation in an Al–1.1Mg–0.5Cu–0.3Si At. Pct Alloy 

      Thronsen, Elisabeth; Mørkeseth, Hanne; Marioara, Calin Daniel; Minakuchi, Kazuhiro; Katsumi, Tetsuya; Marthinsen, Knut; Matsuda, Kenji; Holmestad, Randi (Peer reviewed; Journal article, 2022)
      The effect of 0.03 and 0.08 at. pct Fe additions on the formation of secondary phases in an Al–1.1Mg–0.5Cu–0.3Si at. pct alloy was investigated. Following solution heat treatment and natural aging, the alloys were analyzed ...
    • 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 (Peer reviewed; 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 ...
    • Effects of Germanium, Copper, and Silver Substitutions on Hardness and Microstructure in Lean Al-Mg-Si Alloys 

      Mørtsell, Eva Anne; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Røyset, Jostein; Reiso, Oddvin; Holmestad, Randi (Peer reviewed; Journal article, 2015)
      It is shown that strength loss in a 6060 Al-Mg-Si alloy caused by reduction in solute can be compensated by adding back smaller quantities of Ag, Ge, and Cu. Nine alloys were investigated. Ge was found to be the most ...
    • 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 (Peer reviewed; 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 effects of quench rate and pre-deformation on precipitation hardening in Al–Mg–Si alloys with different Cu amounts 

      Saito, Takeshi; Marioara, Calin Daniel; Røyset, Jostein; Marthinsen, Knut; Holmestad, Randi (Peer reviewed; Journal article, 2014)
      The effects of quench rate after solution heat treatment in combination with 1% pre-deformation on precipitation hardening in three Al–Mg–Si alloys have been investigated by transmission electron microscopy and hardness ...
    • Elemental electron energy loss mapping of a precipitate in a multi-component aluminium alloy 

      Mørtsell, Eva Anne; Wenner, Sigurd; Longo, Paulo; Andersen, Sigmund Jarle; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2016)
      The elemental distribution of a precipitate cross section, situated in a lean Al-Mg-Si-Cu-Ag-Ge alloy, has been investigated in detail by electron energy loss spectroscopy (EELS) and aberration corrected high angle annular ...
    • Enhanced Mechanical Properties in 6082 Aluminum Alloy Processed by Cyclic Deformation 

      Chen, Xuanliang; Mørtsell, Eva Anne; Sunde, Jonas Kristoffer; O, Minho; Marioara, Calin Daniel; Holmestad, Randi; Kobayashi, Equo (Peer reviewed; Journal article, 2021)
      Aging heat treatment is the most commonly used strengthening method for Al–Mg–Si alloys since high-density precipitates will be formed to hinder the movement of dislocations. In the current work, room temperature cyclic ...
    • First principle calculations of pressure dependent yielding in solute strengthened aluminium alloys 

      Frafjord, Jonas; Ringdalen, Inga Gudem; Hopperstad, Odd Sture; Holmestad, Randi; Friis, Jesper (Peer reviewed; Journal article, 2020)
      The pressure dependence of the yield stress in solute strengthened aluminium alloys is investigated by first principle calculations. The solute elements studied are magnesium, silicon and copper. A fixed boundary cluster ...
    • Fully resolved strain field of the β’’ precipitate calculated by density functional theory 

      Frafjord, Jonas; Dumoulin, Stephane; Wenner, Sigurd; Ringdalen, Inga Gudem; Holmestad, Randi; Friis, Jesper (Peer reviewed; Journal article, 2020)
      The β′′ precipitate is the main hardening phase in age hardenable Al-Mg-Si alloys, and it is therefore of major scientific and industrial importance. A full model of the β′′ precipitate cross-section embedded in an aluminium ...
    • 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 ...
    • How calcium prevents precipitation hardening in Al–Mg–Si alloys 

      Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmestad, Randi (Peer reviewed; 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 ...
    • A hybrid aluminium alloy and its zoo of interacting nano-precipitates 

      Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Ervik, Martin; Holmestad, Randi (Peer reviewed; 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 ...
    • 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 (Peer reviewed; Journal article, 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 ...
    • In situ heating TEM observations of evolving nanoscale Al‐Mg‐Si‐Cu precipitates 

      Sunde, Jonas Kristoffer; Wenner, Sigurd; Holmestad, Randi (Peer reviewed; Journal article, 2019)
      This research concerns the precipitation and subsequent dissolution of precipitate phases in an Al–0.86Mg–0.62Si–0.1Cu (at.%) alloy subjected to varying thermal exposure during an in situ heating transmission electron ...
    • Lattice rotations in precipitate free zones in an Al-Mg-Si alloy 

      Christiansen, Emil; Marioara, Calin Daniel; Marthinsen, Knut; Hopperstad, Odd Sture; Holmestad, Randi (Peer reviewed; Journal article, 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 ...