Now showing items 21-40 of 53

    • Extra electron diffraction spots caused by fine precipitates formed at the early stage of aging in Al-Mg-X (X=Si, Ge, Zn)-Cu alloys 

      Matsuda, Kenji; Kawai, Akihiro; Watanabe, Katsumi; Seungwon, Lee; Marioara, Calin Daniel; Wenner, Sigurd; Nishimura, Katsuhiko; Matsuzaki, Teiichiro; Nunomura, Norio; Sato, Tatsuo; Holmestad, Randi; Ikeno, Susumu (Journal article; Peer reviewed, 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. ...
    • 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 (Journal article; Peer reviewed, 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 (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 ...
    • In situ DSC investigation into the kinetics and microstructure of dispersoid formation in Al-Mn-Fe-Si(-Mg) alloys 

      Kemsies, Richard H; Milkereit, Benjamin; Wenner, Sigurd; Holmestad, Randi; Kessler, Olaf (Journal article; Peer reviewed, 2018)
      Dispersoid strengthening in Al-Mn-Fe-Si(-Mg) aluminum wrought alloys can play an important role in applications at elevated temperatures. Fine and evenly distributed dispersoids are needed to increase alloy strength, which ...
    • In situ heating TEM observations of evolving nanoscale Al‐Mg‐Si‐Cu precipitates 

      Sunde, Jonas Kristoffer; Wenner, Sigurd; Holmestad, Randi (Journal article; Peer reviewed, 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 ...
    • Mapping the chemistry within, and the strain around, Al-alloy precipitates at atomic resolution by multi-frame scanning transmission electron microscopy 

      Jones, Lewys; Wenner, Sigurd; Nord, Magnus Kristofer; Ninive, Per Harald; Løvvik, Ole Martin; Marioara, Calin Daniel; Holmestad, Randi; Nellist, Peter (Journal article; Peer reviewed, 2017)
      Al-Mg-Si(-Cu)alloys, used primarily in the transportation sector, are strengthened by nano-sized precipitate particles. There is a plethora of possible phases, depending onwhich elements are added to the alloy ...
    • Muon kinetics in heat treated Al (–Mg)(–Si) alloys 

      Wenner, Sigurd; Nishimura, Katsuhiko; Matsuda, Kenji; Matsuzaki, Teiichiro; Tomono, Dai; Pratt, Francis L.; Marioara, Calin Daniel; Holmestad, Randi (Journal article, 2013)
      Al–Mg–Si alloys are heat-treatable and rely on precipitation hardening for their mechanical strength. We have employed the technique of muon spin relaxation to further our understanding of the complex precipitation sequence ...
    • Muon Spin Relaxation Study of Solute–Vacancy Interactions During Natural Aging of Al-Mg-Si-Cu Alloys 

      Wenner, Sigurd; Marioara, Calin Daniel; Nishimura, Katsuhiko; Matsuda, Kenji; Lee, Seungwon; Namiki, Takahiro; Watanabe, Isao; Matsuzaki, Teiichiro; Holmestad, Randi (Journal article; Peer reviewed, 2019)
      Muon spin relaxation has the unique ability to detect very low concentrations of vacancies and vacancy–solute complexes in solids. In this work, we investigate quaternary Al-Mg-Si-Cu alloys and show that after quenching ...
    • On the formation mechanism of Ba0.85Ca0.15Zr0.1Ti0.15O3 thin films by aqueous chemical solution deposition 

      Khomyakova, Evgeniya; Wenner, Sigurd; Bakken, Kristine; Schultheiß, Jan; Grande, Tor; Glaum, Julia; Einarsrud, Mari-Ann (Journal article; Peer reviewed, 2020)
      Here we report on the development of an environmentally friendly, simple and robust aqueous chemical solution route for the fabrication of Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) thin films. Using a stable aqueous precursor solution, ...
    • Optimising multi-frame ADF-STEM for high-precision atomic-resolution strain mapping 

      Jones, Lewys; Wenner, Sigurd; Nord, Magnus Kristofer; Ninive, Per Harald; Løvvik, Ole Martin; Holmestad, Randi; Nellist, P.D. (Journal article; Peer reviewed, 2017)
      Annular dark-field scanning transmission electron microscopy is a powerful tool to study crystal defects at the atomic scale but historically single slow-scanned frames have been plagued by low-frequency scanning-distortions ...
    • 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 ...
    • Precipitate statistics in an Al-Mg-Si-Cu alloy from scanning precession electron diffraction data 

      Sunde, Jonas Kristoffer; Paulsen, Øyvind; Wenner, Sigurd; Holmestad, Randi (Journal article; Peer reviewed, 2017)
      The key microstructural feature providing strength to age-hardenable Al alloys is nanoscale precipitates. Alloy development requires a reliable statistical assessment of these precipitates, in order to link the microstructure ...
    • 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 behavior in an Al-Cu-Mg-Si alloy during ageing 

      Gazizov, Marat; Marioara, Calin Daniel; Friis, Jesper; Wenner, Sigurd; Holmestad, Randi; Kaibyshev, Rustam (Peer reviewed; Journal article, 2019)
      The precipitation behavior and aging response of an Al-4.9Cu-0.74Mg-0.51Si-0.48Mn-0.1Cr-0.08Ti-0.02Fe (wt. %) alloy was examined in detail after aging at 170 °C with different dwell times up to 96 h. Deformation by ...
    • Precipitation behavior in an Al-Cu-Mg-Si alloy during ageing 

      Gazizov, Marat; Marioara, Calin Daniel; Friis, Jesper; Wenner, Sigurd; Holmestad, Randi; Kaibyshev, Rustam (Peer reviewed; Journal article, 2019)
      The precipitation behavior and aging response of an Al-4.9Cu-0.74Mg-0.51Si-0.48Mn-0.1Cr-0.08Ti-0.02Fe (wt. %) alloy was examined in detail after aging at 170 °C with different dwell times up to 96 h. Deformation by ...
    • Precipitation in a mixed Al-Cu-Mg/Al-Zn-Mg alloy system 

      Wenner, Sigurd; Friis, Jesper; Marioara, Calin Daniel; Holmestad, Randi (Journal article, 2016)
      The precipitation-hardened alloy systems Al–Cu–Mg (2xxx) and Al–Zn–Mg (7xxx) were compositionally combined from a base alloy containing 2% Cu and 1% Mg, added 1–4% Zn (weight fractions). Precipitates in these alloys were ...
    • Probing defects in Al-Mg-Si alloys using muon spin relaxation 

      Wenner, Sigurd; Holmestad, Randi; Matsuda, Kenji; Nishimura, K.; Matsuzaki, T; Tomono, D; Pratt, FL; Marioara, Calin Daniel (Journal article; Peer reviewed, 2012)
      Muon spin methods are very sensitive to nanoscale defects such as trace elements and vacancies in metals. This sensitivity is required when investigating Al-Mg-Si alloys, a complicated system in which diffusion-controlled ...
    • Progress in Understanding Initiation of Intergranular Corrosion on AA6005 Aluminum Alloy with Low Copper Content 

      Kumari, Shilpa; Wenner, Sigurd; Walmsley, John; Lunder, Otto; Nisancioglu, Kemal (Journal article; Peer reviewed, 2019)
      As part of an extensive research program to study recent, unexpected intergranular corrosion (IGC) on 6xxx series aluminum alloys (AlMgSi), this paper investigates the mechanism of initiation and early propagation of IGC ...