Pui-Wai Ma

Atomistic modelling and experimental study of microstructural evolution in nanocrystalline iron subjected to irradiation

Ivan Tolkachev, Daniel R. Mason, Max Boleininger, Pui-Wai Ma et autres

Ab initio relaxation volumes of transition metal solutes in iron and tungsten

Andrew R. Warwick, Jacob B. J. Chapman, D. Nguyen-Manh, Pui-Wai Ma et autres

Atomic volume differences determine the structure and phase stability of alloys. To assess the size mismatch, atomic volumes of pure elements, derived from their elemental crystalline states, are normally used as a reference. Using calculations, we show that substitutional transition metal solute …

Irradiation tolerance of nanocrystalline Fe and FeCr: Large scale atomistic simulations and matched experiments

Ivan Tolkachev, Felix Hofmann, Daniel J. Long, Daniel R. Mason et autres

During operation, deuterium-tritium fusion devices generate high-energy neutrons that penetrate the lattice of reactor components, triggering collision cascades. The resulting material defects cause degradation of the thermal and mechanical properties of the constituent material. Nanocrystalline materials, characterised by their small grain size, …

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Irradiation tolerance of nanocrystalline Fe and FeCr: Large scale atomistic simulations and matched experiments

Ivan Tolkachev, Felix Hofmann, Daniel J. Long, Daniel R. Mason et autres

During operation, deuterium-tritium fusion devices generate high-energy neutrons that penetrate the lattice of reactor components, triggering collision cascades. The resulting material defects cause degradation of the thermal and mechanical properties of the constituent material. Nanocrystalline materials, characterised by their small grain size, …

gb (code pays fourni par la source)

Point defect structures in hexagonal close packed metals and across the Periodic Table

Andrew R. Warwick, Pui-Wai Ma, S. L. Dudarev

We present a comprehensive dataset of formation energies and elastic properties of intrinsic point defects across all the transition and rare earth hexagonal close packed (hcp) metals, as well as metalloid elements with hcp crystal structure. Point defect properties appear weakly correlated …

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Author response for "Atomistic simulations of irradiation damage on the engineering timescale: Examining the dose rate effect in tungsten"

Max Boleininger, Daniel R. Mason, T. Schwarz‐Selinger, Pui-Wai Ma

Atomistic and experimental study of microstructural evolution in nanocrystalline iron subjected to irradiation

Ivan Tolkachev, Daniel R. Mason, Max Boleininger, Pui-Wai Ma et autres

Nanocrystalline materials have been proposed for use in future fusion reactors due to their high grain boundary density that may act as a sink for irradiation-induced defects. We use molecular dynamics to model collision cascades in nanocrystalline iron and compare the damage …

Review of point defect structures in hexagonal close packed metals and across the Periodic Table

Andrew R. Warwick, Pui-Wai Ma, S. L. Dudarev

We present a comprehensive ab initio dataset of formation energies and elastic properties of intrinsic point defects across all the transition and rare earth hexagonal close packed (hcp) metals, as well as metalloid elements with hcp crystal structure. Point defect properties appear …

Simulations of nanocrystalline iron formation under high shear strain

Ivan Tolkachev, Pui-Wai Ma, Daniel R. Mason, Felix Hofmann

High-shear methods have long been used in experiments to refine grain structures in metals, yet the underlying mechanisms remain elusive. We demonstrate a refinement process using molecular dynamic simulations of iron wherein nanocrystalline structures are generated from initially perfect lattices under high-shear …

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Atomistic simulations of irradiation damage on the engineering timescale: examining the dose rate effect in tungsten

Max Boleininger, Daniel R. Mason, T. Schwarz‐Selinger, Pui-Wai Ma

We present a parameter-free method for simulating microstructural evolution of metals under irradiation at realistic dose-rates with full atomistic resolution.

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Activation Functions for "A Feedforward Unitary Equivariant Neural Network"

Pui-Wai Ma

In our previous work [Ma and Chan (2023)], we presented a feedforward unitary equivariant neural network. We proposed three distinct activation functions tailored for this network: a softsign function with a small residue, an identity function, and a Leaky ReLU function. While …

Nanocrystalline tungsten at high radiation exposure

Pui-Wai Ma, Daniel R. Mason, Steven Van Boxel, S. L. Dudarev

Evolution of nanocrystalline (NC) tungsten under radiation exposure is investigated by atomic scale simulations in the low temperature high dose limit. Statistical analysis of samples containing at least a million atoms, with grain size varying from 5 nm to 20 nm, shows …

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