• A hybrid aluminium alloy and its zoo of interacting nano-precipitates 

      Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Ervik, Martin; Holmestad, Randi (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 ...
    • Accurately measured precipitate–matrix misfit in an Al–Mg–Si alloy by electron microscopy 

      Wenner, Sigurd; Holmestad, Randi (Journal article, 2016)
      The age-hardenable Al–Mg–Si alloy system is strengthened by needle-shaped coherent β″ phase precipitates. Using distortion-corrected high-resolution scanning transmission electron microscopy images, we measure the considerable ...
    • 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 (Journal article; Peer reviewed, 2021)
      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 (Journal article; Peer reviewed, 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 (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 (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 (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, 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 ...
    • 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 (Journal article; Peer reviewed, 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 ...
    • Density Functional Theory Studies of Precipitate Interfaces in Aluminium Alloys, with Focus on Theta'-Al2Cu 

      Østli, Philip (Master thesis, 2016)
      The atomic structure of bulk crystal of aluminium and the precipitate phase $\theta^\prime$ connected to age-hardening of Al-Cu alloys have been studied using Density Functional Theory (DFT). The lattice constant of ...
    • Directionality and column arrangement principles of precipitates in Al-Mg-Si-(Cu) and Al-Mg-Cu linked to line defect in Al 

      Andersen, Sigmund Jarle; Marioara, Calin Daniel; Friis, Jesper; Bjørge, Ruben; Du, Qiang; Ringdalen, Inga Gudem; Wenner, Sigurd; Mørtsell, Eva Anne; Holmestad, Randi; Saito, Takeshi; Røyset, Jostein; Reiso, Oddvin (Journal article, 2016)
      In the structures of all metastable precipitates in Al-Mg-Cu and Al-Mg-Si alloys, we find that column surrounding of an element column in the needle/lath direction order according to simple principles. Advanced transmission ...
    • Dislocation dynamics study of precipitate hardening in Al-Mg-Si alloys with input from experimental characterization 

      Ringdalen, Inga Gudem; Wenner, Sigurd; Friis, Jesper; Marian, Jaime (Journal article; Peer reviewed, 2017)
      Partial aging of AA6060 aluminum alloys is known to result in a microstructure characterized by needle-shaped Si/Mg-rich precipitates. These precipitates belong to the non-equilibrium β″ phase and are coherent with the ...
    • 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 (Journal article; Peer reviewed, 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 ...
    • Effect of copper on fine precipitates at the early stage of aging in Al-Mg-X (X=Si, Ge, Zn) alloys 

      Matsuda, Kenji; Kawai, Akihiro; Watanabe, Katsumi; Lee, Seungwon; Marioara, Calin Daniel; Wenner, Sigurd; Nishimura, Katsuhiko; Matsuzaki, Teiichiro; Nunomura, Norio; Sato, Tatsuo; Holmestad, Randi; Ikeno, Susumu (Journal article, 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. ...
    • Effect of different microstructural features on the hydrogen embrittlement susceptibility of alloy 718 

      Stenerud, Gaute; Wenner, Sigurd; Olsen, Jim Stian; Johnsen, Roy (Journal article; Peer reviewed, 2018)
      Due to its high strength and acceptable corrosion resistance, Alloy 718 is a viable material for the use in subsea applications. The alloy's susceptibility to hydrogen embrittlement is however limiting its viability. In ...
    • Effect of room temperature storage time on precipitation in Al-Mg-Si(-Cu) alloys with different Mg/Si ratios 

      Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmestad, Randi (Journal article; Peer reviewed, 2012)
      The effect of natural ageing time before artificial ageing has been investigated in four Al – Mg – Si(– Cu) alloys, with 0.4 % Mg + 0.8 % Si and 0.8 % Mg + 0.4 % Si, both with and without 0.14 at.% Cu. The precipitate ...
    • 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; Torsæter, Malin; Gawel, Bartlomiej; Wenner, Sigurd (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 ...
    • 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 (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 ...