Blar i SINTEF Open på forfatter "Holmestad, Randi"
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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 ... -
Linking mechanical properties to precipitate microstructure in three Al-Mg-Si(-Cu) alloys
Sunde, Jonas Kristoffer; Lu, Feng; Marioara, Calin Daniel; Holmedal, Bjørn; Holmestad, Randi (Peer reviewed; Journal article, 2021)The mechanical properties of age hardenable Al alloys depend strongly on the precipitate microstructure. This work has investigated the relationship between properties such as strength and ductility and the distribution ... -
Local mechanical properties and precipitation inhomogeneity in large-grained Al–Mg–Si alloy
Hagen, Anette Brocks; Wenner, Sigurd; Bjørge, Ruben; Wan, Di; Marioara, Calin Daniel; Holmestad, Randi; Ringdalen, Inga Gudem (Peer reviewed; Journal article, 2022)Al–Mg–Si (6xxx series) alloys show excellent mechanical properties due to the precipitates formed during heat treatment. However, heat treatment of these alloys results in a soft precipitation free zone (PFZ) close to grain ... -
Magnetic domain configuration of (111)-oriented LaFeO3 epitaxial thin films
Hallsteinsen, Ingrid; Moreau, Magnus; Chopdekar, R.V.; Christiansen, Emil; Nord, Magnus Kristofer; Vullum, Per Erik; Grepstad, Jostein; Holmestad, Randi; Selbach, Sverre Magnus; Scholl, A; Arenholz, E; Folven, Erik; Tybell, Per Thomas Martin (Peer reviewed; Journal article, 2017)In antiferromagnetic spintronics control of the domains and corresponding spin axis orientation is crucial for devices. Here we investigate the antiferromagnetic axis in (111)-oriented LaFeO3/SrTiO3, which is coupled to ... -
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 (Peer reviewed; Journal article, 2017) -
Multislice image simulations of sheared needle‐like precipitates in an Al‐Mg‐Si alloy
Christiansen, Emil; Ringdalen, Inga Gudem; Bjørge, Ruben; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2020)The image contrast of sheared needle‐like precipitates in the Al‐Mg‐Si alloy system is investigated with respect to shear‐plane positions, the number of shear‐planes, and the active matrix slip systems through multislice ... -
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 (Peer reviewed; 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 (Peer reviewed; Journal article, 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 ... -
Nano-scale characterisation of sheared β” precipitates in a deformed Al-Mg-Si alloy
Christiansen, Emil; Marioara, Calin Daniel; Holmedal, Bjørn; Hopperstad, Odd Sture; Holmestad, Randi (Journal article; Peer reviewed, 2019)This paper compares the nano-scale structure of β” precipitates in a peak-aged Al-Mg-Si alloy before and after deformation. Three complementary advanced transmission electron microscopy techniques are used to reveal the ... -
Nanostructural Analysis of Co-Re/γ-Al2O3 Fischer-Tropsch Catalyst by TEM and XRD
Dehghan-Niri, Roya; Tsakoumis, Nikolaos E.; Voronov, Alexey; Holmen, Anders; Holmestad, Randi; Vullum, Per Erik; Borg, Øyvind; Rytter, Erling; Rønning, Magnus; Walmsley, John (Peer reviewed; Journal article, 2022)A rhenium promoted Fischer-Tropsch (FT) cobalt catalyst supported on γ-Al2O3 has been investigated by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD), before and after reduction. Electron diffraction, ... -
On intermetallic phases formed during interdiffusion between aluminium alloys and stainless steel
Bergh, Tina; Arbo, Siri Marthe; Hagen, Anette Brocks; Blindheim, Jørgen; Friis, Jesper; Khalid, Muhammad Zeeshan; Ringdalen, Inga Gudem; Holmestad, Randi; Westermann, Ida; Vullum, Per Erik (Peer reviewed; Journal article, 2022)One of the major challenges in welding of aluminium (Al) alloys and steels is the growth of brittle intermetallic phases, which depends on the thermomechanical processing history and the alloying elements. This work focuses ... -
On the Atomic Structure of the β′′ Precipitate by Density Functional Theory
Frafjord, Jonas; Ringdalen, Inga Gudem; Holmestad, Randi; Friis, Jesper (Peer reviewed; Journal article, 2023)The substitution of elements into the precipitate in the 6xxx-series of aluminium alloys is an interface sensitive problem. The strain caused by the misfit between the precipitate and the matrix interacts with the size ... -
On the microstructural origins of improvements in conductivity by heavy deformation and ageing of Al-Mg-Si alloy 6101
Sunde, Jonas Kristoffer; Marioara, Calin Daniel; Wenner, Sigurd; Holmestad, Randi (Peer reviewed; Journal article, 2021)This work has examined an Al-0.54Mg-0.38Si (at.%) conductor alloy (6101) subjected to two different thermomechanical processing routes. Conventional solution treatment, quenching, and artificial ageing (170 °C) was compared ... -
On the Use of a Cluster Identification Method and a Statistical Approach for Analyzing Atom Probe Tomography Data for GP Zones in Al–Zn–Mg(–Cu) Alloys
Shah, Sohail; Thronsen, Elisabeth; de gauser, Frederic; hatzoglou, constantinos; Marioara, Calin Daniel; Holmestad, Randi; Holmedal, Bjørn (Peer reviewed; Journal article, 2023)Early-stage clustering in two Al–Mg–Zn(–Cu) alloys has been investigated using atom probe tomography and transmission electron microscopy. Cluster identification by the isoposition method and a statistical approach based ... -
Precipitate/matrix incompatibilities related to the {111}Al Ω plates in an Al-Cu-Mg-Ag alloy
Gazizov, M.R.; Boev, A.O.; Marioara, Calin Daniel; Holmestad, Randi; Aksyonov, D.A.; Gazizova, M.Yu.; Kaibyshev, R.O. (Peer reviewed; Journal article, 2021)The atomic structure of Ω plates forming on {111}Al planes in an Al-Cu-Mg-Ag alloy has been investigated by Z-contrast atomic-resolution scanning transmission electron microscopy imaging and ab initio density functional ... -
Precipitates in aluminium alloys
Andersen, Sigmund Jarle; Marioara, Calin Daniel; Friis, Jesper; Wenner, Sigurd; Holmestad, Randi (Peer reviewed; Journal article, 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 (Journal article; Peer reviewed, 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 an extruded AA7003 aluminium alloy: Observations of 6xxx-type hardening phases
Lervik, Adrian; Marioara, Calin Daniel; Kadanik, Maria; Walmsley, John; Milkereit, Benjamin; Holmestad, Randi (Journal article; Peer reviewed, 2019)Precipitation behaviour in an industrially extruded AA7003 alloy has been studied using Transmission Electron Microscopy (TEM) together with Differential Scanning Calorimetry (DSC). Air Cooling (AC) after solution heat ... -
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, 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 ... -
Quantitative analysis of {100} Al plate/lath- and Al rod-shaped precipitates in an aged Al-Cu-Mg-Si alloy using TEM
Marat, Gazizov; Holmestad, Randi; Marioara, Calin Daniel; Kaibyshev, Rustam (Peer reviewed; Journal article, 2021)Precipitate parameters, such as length, diameter and thickness of rationally oriented {100}Al plate/lath-shaped and Al rod-shaped precipitates in an age-hardenable Al-Cu-MgSi alloy have been examined quantitatively. An ...