Blar i NTNU Open på forfatter "Holmestad, Randi"
-
Interface energy determination for the fully coherent β'' phase in Al-Mg-Si: making a case for a first principles based hybrid atomistic modelling scheme
Ehlers, Flemming J H; Dumoulin, Stephane; Marthinsen, Knut; Holmestad, Randi (Journal article, 2013)Multiscale modelling of hardening precipitate interfaces in alloy design This project will develop a new multiscale modelling scheme used to investigate hardening precipitate interfaces in metal alloys. The major aim is ... -
Interface Microstructure and Tensile Properties of a Third Generation Aluminium-Steel Butt Weld Produced Using the Hybrid Metal Extrusion & Bonding (HYB) Process
Sandnes, Lise; Bergh, Tina; Grong, Øystein; Holmestad, Randi; Vullum, Per Erik; Berto, Filippo (Peer reviewed; Journal article, 2021)The Hybrid Metal Extrusion & Bonding (HYB) process is a patented solid state joining method for metals which utilizes filler material additions to consolidate the weld. In the present investigation the interface microstructure ... -
Interfacial and strain energy analysis from ab initio based hierarchical multi-scale modelling: the Al–Mg–Si alloy β'' phase
Ehlers, Flemming J H; Dumoulin, Stephane; Marthinsen, Knut; Holmestad, Randi (Journal article, 2014)Precipitate-host lattice interface studies have not traditionally been viewed as requiring hybrid model schemes for accurate determination of the interfacial and strain energies. On the other hand, the interfaces of main ... -
Intermetallic Phase Layers in Cold Metal Transfer Aluminium-Steel Welds with an Al–Si–Mn Filler Alloy
Bergh, Tina; Ånes, Håkon Wiik; Aune, Ragnhild; Wenner, Sigurd; Holmestad, Randi; Ren, Xiaobo; Vullum, Per Erik (Peer reviewed; Journal article, 2023) -
Investigating the precipitates in the heat affected zone of a HYB welded Al-Mg-Si-Cu alloy using transmission electron microscopy
Korsvold, Håkon Longva (Master thesis, 2023)Klimaendringer grunnet menneskeskapte klimagassutslipp har gjort det nødvendig å utvikle mer energieffektive løsninger i alle deler av sammfunnet. En av de største utslippskildene er transport av mennesker og varer, som ... -
Lattice rotations in precipitate free zones in an Al-Mg-Si alloy
Christiansen, Emil; Marioara, Calin Daniel; Marthinsen, Knut; Hopperstad, Odd Sture; Holmestad, Randi (Journal article; Peer reviewed, 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 (Journal article; Peer reviewed, 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 (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 ... -
Methodology to Improve Strain Measurement in III–V Semiconductors Materials
Vatanparast, Maryam; Vullum, Per Erik; Nord, Magnus Kristofer; Reenaas, Turid Worren; Holmestad, Randi (Journal article; Peer reviewed, 2017)Geometric phase analysis (GPA), a fast and simple Fourier space method for strain analysis, can give useful information on accumulated strain and defect propagation in multiple layers of InAs/GaAs quantum dot (QD) materials. ... -
Microstructural and mechanical characterisation of a second generation hybrid metal extrusion & bonding aluminium-steel butt joint
Bergh, Tina; Sandnes, Lise; Johnstone, Duncan Neil; Grong, Øystein; Berto, Filippo; Holmestad, Randi; Midgley, Paul Anthony; Vullum, Per Erik (Peer reviewed; Journal article, 2020)Hybrid metal extrusion & bonding (HYB) is a joining method that enables solid-state bonding by combining addition of aluminium filler material through continuous extrusion with pressure exerted by a rotating steel tool. ... -
Microstructural Characterisation of Features Related to Grain Boundary Corrosion Phenomena in Aluminium Alloys
Lervik, Adrian (Doctoral theses at NTNU;2020:260, Doctoral thesis, 2020)Aluminium (Al) alloys are of great interest as components for the automotive and aerospace industries. These alloys have great mechanical properties and are lighter than their alternatives. Light alloys will effectively ... -
The microstructural origin of a hardness double-peak in an age-hardened EN-AW 6082
Hell, Christoph Martin; Holmedal, Bjørn; Bjørge, Ruben; Marioara, Calin Daniel; Holmestad, Randi (Peer reviewed; Journal article, 2023)In this study, the origin of a double-peak during artificial aging of an EN-AW 6082 is analyzed with (S)TEM. The acquired TEM data is used as an input into a strength model by Holmedal [1] to explore the origin of the ... -
Modeling over-ageing in Al-Mg-Si alloys by a multi-phase CALPHAD-coupled Kampmann-Wagner Numerical model
Du, Qiang; Tang, Kai; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Holmedal, Bjørn; Holmestad, Randi (Journal article, 2017)The formation of the equilibrium precipitation phase during ageing treatment of Al-Mg-Si alloys is preceded by a series of metastable phases. Given longer ageing time, higher ageing temperature or elevated temperature ... -
Multi-scale Modelling of Precipitation in Alloys
Kleiven, David (Doctoral theses at NTNU;2022:37, Doctoral thesis, 2022)Numerical modelling is becoming an increasingly important tool when developing new materials. However, material properties depend on physical phenomena spanning across a wide range of length and time scales. Therefore, it ... -
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 urn:x-wiley:00222720:media:jmi12901:jmi12901-math-0001 precipitates in the Al‐Mg‐Si alloy system is investigated with respect to shear‐plane positions, the number of shear‐planes, ... -
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 ... -
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 ...