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UKAEA-CCFE-PR(19)192019
Extensive Monte Carlo simulations of lithium oxide, Li2O, an important material for fusion applications over a wide range of temperatures have been performed. In the low temperature range 1 – 500 K, quantum corrections to the enthalpy and unit cell size were determined. We show that the classical Monte Carlo underestimates both these q…
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CCFE-PR(17)062017
Using an ab initio approach, we explore the stability of small vacancy and vacancychromium clusters in dilute body-centred cubic Fe-Cr alloys. To explain experimental observations described in C.D. Hardie et al., J. Nucl. Mater. 439, 33 (2013) and showing the occurrence of Cr segregation in low-Cr alloys, we investigate if chromium can form stable …
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2015
Understanding the behaviour of solid solutions over wide ranges of temperature and pressure remains a major challenge to both theory and experiment. Here we report a detailed exchange Monte Carlo study using a classical ionic model of the model perovskite parascandolaite-neighborite (K,Na)MgF3 solid solution and its end-members for temperatures in …
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CCFE-PR(15)1202015
Low-energy magnetic states and finite-temperature properties of Cr nanoclusters in bulk bcc Fe and Fe nanoclusters in bulk Cr are investigated using density functional theory (DFT) and the Heisenberg-Landau Hamiltonian based magnetic cluster expansion (MCE). We show, by means of noncollinear magnetic DFT calculations, that magnetic frustration caus…
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CCFE-PR(15)1072015
The phase stability of fcc and bcc magnetic binary Fe-Cr, Fe-Ni, and Cr-Ni alloys, and ternary Fe-Cr-Ni alloys is investigated using a combination of density functional theory (DFT), cluster expansion (CE), and magnetic cluster expansion (MCE) approaches. Energies, magnetic moments, and volumes of more than 500 alloy structures have been evaluated …
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CCFE-PR(15)632015
A Magnetic Cluster Expansion model for ternary face-centered cubic Fe-Ni-Cr alloys has been developed, using DFT data spanning binary and ternary alloy configurations. Using this Magnetic Cluster Expansion model Hamiltonian, we perform Monte Carlo simulations and explore magnetic structures of alloys over the entire range of compositions, consideri…
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2014
A model lattice ab initio parameterized Heisenberg–Landau magnetic cluster expansion Hamiltonian spanning a broad range of alloy compositions and a large variety of chemical and magnetic configurations has been developed for face-centered cubic Fe–Ni alloys. The thermodynamic and magnetic properties of the alloys are explored using configuratio…
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2013
We develop a Magnetic Cluster Expansion (MCE) model for binary bcc and fcc Fe–Cr alloys, as well as for fcc Fe-Ni alloys, and apply it to the investigation of magnetic properties of these alloys over a broad interval of concentrations, and over a broad interval of temperatures extending well over 1000 K. We show how an MCE-based Monte Carlo study…
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2013
The development of quantitative models for radiation damage effects in iron, iron alloys and steels, particularly for the high temperature properties of the alloys, requires understanding of magnetic interactions, which control the phase stability of ferritic-martensitic, ferritic, and austenitic steels. In this work, disordered magnetic configurat…
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2012
We present a combined experimental and computational study of high-temperature magnetic properties of Fe-Cr alloys with chromium content up to about 20 at.%. Magnetic Cluster Expansion method is applied to model the magnetic properties of random Fe-Cr alloys, and in particular the Curie transition temperature, as functions of alloy composition. We …
Showing 11 - 20 of 25 UKAEA Paper Results