• Atomic structure of solute clusters in Al-Zn-Mg alloys 

      Lervik, Adrian; Thronsen, Elisabeth; Friis, Jesper; Marioara, Calin Daniel; Wenner, Sigurd; Bendo, Artenis; Matsuda, Kenji; Holmestad, Randi; Andersen, Sigmund Jarle (Peer reviewed; Journal article, 2020)
      Scanning transmission electron microscopy imaging of Al–Zn–Mg alloys has provided new information on the atomic structures of solute rich clusters forming from a supersaturated solid solution at low temperatures. A unique ...
    • Atomic structures of precipitates in Al–Mg–Si alloys with small additions of other elements 

      Saito, Takeshi; Mørtsell, Eva Anne; Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Friis, Jesper; Matsuda, Kenji; Holmestad, Randi (Peer reviewed; Journal article, 2018)
      In Al–Mg–Si alloys, additions of only a few weight percent of Mg and Si enable formation of hardening precipitates during heat treatment. The precipitation is complex and is influenced by chemical compositions and ...
    • Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy 

      Wenner, Sigurd; Jones, Lewys; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2017)
      Scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDS) is a common technique for chemical mapping in thin samples. Obtaining high-resolution elemental maps in the STEM is ...
    • Atomic-resolution electron energy loss studies of precipitates in an Al-Mg-Si-Cu-Ag alloy 

      Wenner, Sigurd; Marioara, Calin Daniel; Ramasse, Quentin; Kepaptsoglou, Despoina Maria; Hage, Fredrik Sydow; Holmestad, Randi (Peer reviewed; Journal article, 2014)
      Aberration-corrected scanning transmission electron microscopy combined with electron energy loss spectroscopy has been used to determine the distribution of Cu and Ag atomic columns of precipitates in an Al–Mg–Si–Cu–Ag ...
    • Atomic-resolution elemental mapping of precipitates in a 7449 aluminium alloy 

      Wenner, Sigurd; Marioara, Calin Daniel; Lefebvre, Williams; Ramasse, Quentin; Kepaptsoglou, Despoina Maria; Hage, Fredrik Sydow; Holmestad, Randi (Peer reviewed; Journal article, 2014)
      The high-strength weldable 7xxx series of aluminium alloys are of great importance to the aeronautics industry. Only recently, the complex structures of the AlZnMg hardening precipitates have been solved by HAADFSTEM imaging ...
    • Clustering and Vacancy Behavior in High- and Low-Solute Al-Mg-Si Alloys 

      Wenner, Sigurd; Nishimura, Katsuhiko; Matsuda, Kenji; Matsuzaki, Teiichiro; Tomono, Dai; Pratt, Francis L.; Marioara, Calin Daniel; Holmestad, Randi (Journal article; Peer reviewed, 2014)
      The precipitate microstructure and vacancy distribution in Al-Mg-Si alloys with different amounts of solute and different heat treatments were investigated by transmission electron microscopy and muon spin relaxation ...
    • Copper enriched by dealloying as external cathode in intergranular corrosion of aluminium alloy AA6005 

      Kumari, Shilpa; Wenner, Sigurd; Walmsley, John; Lunder, Otto; Nisancioglu, Kemal (Journal article; Peer reviewed, 2019)
      The purpose of this work is to understand the role of Cu in the propagation mechanism of IGC on extruded alloy AA6005-T5. The constituent Cu segregates as a Cu-rich nanolayer, together with the formation of a solute depleted ...
    • Copper enrichment on aluminium surfaces after electropolishing and its effect on electron imaging and diffraction 

      Wenner, Sigurd; Lervik, Adrian; Thronsen, Elisabeth; Marioara, Calin Daniel; Kubowicz, Stephan; Holmestad, Randi (Peer reviewed; Journal article, 2020)
      Electropolishing is the most common method of preparing samples of aluminium alloys for scanning and transmission electron microscopy, as it yields a good surface quality and large flat, electron-transparent areas. Like ...
    • The correlation between intergranular corrosion resistance and copper content in the precipitate microstructure in an AA6005A alloy 

      Marioara, Calin Daniel; Lervik, Adrian; Grønvold, Julie; Lunder, Otto; Wenner, Sigurd; Furu, Trond; Holmestad, Randi (Peer reviewed; Journal article, 2018)
      A positive correlation is observed between the amount of Cu incorporated in hardening precipitates and intergranular corrosion resistance in an artificially aged Cu-containing 6005A alloy. Three mechanisms have been ...
    • Crystallographic relationships of T-/S-phase aggregates in an Al–Cu–Mg–Ag alloy 

      Sunde, Jonas Kristoffer; Johnstone, D.N.; Wenner, Sigurd; Van Helvoort, Antonius; Midgley, Paul A.; Holmestad, Randi (Peer reviewed; Journal article, 2018)
      T-(Al20Cu2Mn3) phase dispersoids are important for limiting recovery and controlling grain growth in Al-Cu alloys. However, these dispersoids can also reduce precipitation hardening by acting as heterogeneous nucleation ...
    • Effect of copper addition on the cluster formation behavior of Al-Mg-Si, Al-Zn-Mg, and Al-Mg-Ge in the natural aging 

      Hatakeyama, Daichi; Nishimura, Katsuhiko; Matsuda, Kenji; Namiki, Takahiro; Lee, Seungwon; Nunomura, Norio; Aida, Tetsuo; Matsuzaki, Teiichiro; Holmestad, Randi; Wenner, Sigurd; Marioara, Calin Daniel (Peer reviewed; Journal article, 2018)
      The time-dependent resistivity of Al-Mg-Si(-Cu), Al-Zn-Mg(-Cu), and Al-Mg-Ge(-Cu) alloys are studied over a range of constant temperatures between 255 K and 320 K. The resistivity vs time curves for the samples show three ...
    • 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 Water Content and Temperature on Bulk Resistivity of Hybrid Cement/Carbon Nanofiber Composites 

      Gawel, Kamila; Taghipour, Ali; Bjørge, Ruben; Wenner, Sigurd; Gawel, Bartlomiej; Ghaderi, Amir; Cerasi, Pierre (Peer reviewed; Journal article, 2020)
      Cement nanocomposites with carbon nanofibers (CNFs) are electrically conductive and sensitive to mechanical loads. These features make them useful for sensing applications. The conductive and load sensing properties are ...
    • Electrochemical enhancement and inhibition of calcium carbonate deposition 

      Edvardsen, Laura; Gawel, Kamila; Wenner, Sigurd; Gawel, Bartlomiej; Torsæter, Malin (Peer reviewed; Journal article, 2020)
      Calcium carbonate is by far the most widespread scaling material. Its deposition in pipes and flowlines has been a long-standing problem for many industries. Hence, a lot of research is devoted to scale inhibition. One of ...
    • Electrochemically Enhanced Deposition of Minerals from Synthetic Reservoir Brine 

      Edvardsen, Laura; Emmel, Benjamin Udo; Bhuiyan, Mohammad Hossain; Wenner, Sigurd; Gawel, Kamila; Torsæter, Malin (SINTEF Proceedings;7, Chapter; Peer reviewed; Conference object, 2021)
      In this paper we ask the question whether or not electrochemically enhanced deposition of minerals can be utilized to repair leakage paths existing in cement plugs in wells. Electrical polarization of two electrodes may ...
    • 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 ...
    • Filler metal distribution and processing stability in laser-arc hybrid welding of thick HSLA steel 

      Bunaziv, Ivan; Wenner, Sigurd; Ren, Xiaobo; Frostevarg, Jan; Kaplan, Alexander F.H.; Akselsen, Odd Magne (Peer reviewed; Journal article, 2020)
      Welds made by high power laser beam have deep and narrow geometry. Addition offiller wire by the arc source,forming the laser-arc hybrid welding (LAHW) process, is very important to obtain required mechanical prop-erties. ...
    • 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 ...