• Scanning Precession Electron Diffraction to aid Aluminum Alloy Development 

      Sunde, Jonas Kristoffer; Christiansen, Emil; Thronsen, Elisabeth; Wenner, Sigurd; Marioara, Calin Daniel; Van Helvoort, Antonius; Holmestad, Randi (Peer reviewed; Journal article, 2019)
    • Stress Corrosion Cracking in an Extruded Cu-Free Al-Zn-Mg Alloy 

      Lervik, Adrian; Walmsley, John Charles; Lodgaard, Lars; Marioara, Calin Daniel; Johnsen, Roy; Lunder, Otto; Holmestad, Randi (Peer reviewed; Journal article, 2020)
      Stress corrosion cracking (SCC) in Cu-free Al-Zn-Mg (7xxx) aluminium alloys limits its use in many applications. In this work, we study in detail the microstructure of a peak and slightly overaged condition in an AA7003 ...
    • 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 (Peer reviewed; Journal article, 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 (Peer reviewed; 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 ...
    • A study of the influence of precipitate free zones on the strain localization and failure of the aluminium alloy AA7075-T651 

      Fourmeau, Marion; Marioara, Calin Daniel; Børvik, Tore; Benallal, Ahmed; Hopperstad, Odd Sture (Peer reviewed; Journal article, 2015)
      Age-hardened aluminium alloys have various degrees of precipitate-free zones (PFZs) along grain boundaries (GBs). The PFZs are weak zones and their existence promotes combined transgranular and intergranular fracture, thus ...
    • 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 (Peer reviewed; Journal article, 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 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 evolution of precipitate crystal structures in an Al-Mg-Si(-Cu) alloy studied by a combined HAADF-STEM and SPED approach 

      Sunde, Jonas Kristoffer; Marioara, Calin Daniel; Van Helvoort, Antonius; Holmestad, Randi (Journal article; Peer reviewed, 2018)
      This work presents a detailed investigation into the effect of a low Cu addition (0.01 at.%) on precipitation in an Al-0.80Mg-0.85Si alloy during ageing. The precipitate crystal structures were assessed by scanning ...
    • A transmission electron microscopy study of precipitate phases that form during operation in a heat exchanger alloy 

      Marioara, Calin Daniel; Friis, Jesper; Hersent, Emmanuel; Oskarsson, Anders (Peer reviewed; Journal article, 2019)
      During manufacturing of heat exchangers, the core material is cladded with a lower-melting point alloy, rolled into thin strips before being formed and finally brazed at an elevated temperature. After a period of natural ...
    • 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 ...
    • µSR study of Al-0.67%Mg-0.77%Si alloys 

      Nishimura, Katsuhiko; Matsuda, Kenji; Komaki, R; Nunomura, Norio; Wenner, Sigurd; Holmestad, Randi; Matsuzaki, Teiichiro; Watanabe, Isao; Pratt, Francis L.; Marioara, Calin Daniel (Peer reviewed; Journal article, 2014)
      Zero-field muon spin relaxation measurements were carried out with Al-0.67%Mg- 0.77%Si alloys in the temperature range from 20 K to 300 K. Observed relaxation spectra were compared with the relaxation functions calculated ...