A reactive interatomic potential based on an analytical bond-order scheme is developed for the ternary system W–C–H. The model combines Brenner’s hydrocarbon with parameter sets W–W, W–C, and W–H interactions adjusted to materials properties of reference structures different local atomic coordinations including tungsten carbide, molecules, as well H dissolved in bulk W. has been tested various scenarios, such surface, defect, melting properties, none which were considered fitting. intended...

The experimentally observed large difference in the depths of hydrogen and helium clusters formed tungsten still lacks a fundamental explanation. Using density functional theory calculations, molecular dynamics simulations, kinetic Monte Carlo we show that mechanism behind different clustering is significantly behaviors interstitial H He atoms W: H–H states are unstable for small interatomic distances whereas He–He strongly bound.

Stainless steels found in real-world applications usually have some C content the base Fe-Cr alloy, resulting hard and dislocation-pinning carbides-Fe3C (cementite) Cr23C6-being present finished steel product. The higher complexity of microstructure has implications, for example, elastic properties evolution defects such as Frenkel pairs dislocations. This makes it necessary to re-evaluate effects basic radiation phenomena not simply rely on results obtained from purely metallic alloys. In...

The useful properties of steels are due to a complicated microstructure containing iron and chromium carbides. Only some basic physical these carbides known with high precision, although the may have vital impact on performance longevity steel. To improve this situation, we performed extensive density-functional theory calculations several quantitative results in perfect agreement relative empirical stability Also, contradiction experimental data, find that Cr23C6 responsible for hardness...

Analytical bond-order potentials for beryllium, beryllium carbide and hydride are presented. The reactive nature of the formalism makes suitable simulations non-equilibrium processes such as plasma-wall interactions in fusion reactors. Be Be-C were fitted to ab initio calculations well experimental data several different atomic configurations Be-H molecule defect used determining parameter set. Among other tests, sputtering, melting quenching performed order check transferability potentials....

An analytical bond-order interatomic potential has been developed for the iron-carbon system use in molecular-dynamics and Monte Carlo simulations. The successfully fitted to cementite H\"agg carbide, which are most important crystalline polytypes among many known metastable iron carbide phases. Predicted properties of other carbides simplest point defects good reasonable agreement with available data from experiments density-functional theory calculations. correctly describes melting...

The role of self-trapping and defect trapping hydrogen helium implanted into tungsten has been investigated using density functional theory (DFT) calculations, molecular dynamics simulations, kinetic Monte Carlo simulations (KMCSs). potential energy curves or pairs were obtained by dynamics, the most essential states was checked with DFT. Under assumptions bubble formation due to similiar impurity atoms (self-trapping) defects, KMCSs carried out parameters from implantation experiments....

For the first time, isothermal equiaxed solidification of a metallic alloy has been observed in situ space, providing unique benchmark experimental data. The experiment was completed on board MASER 13 sounding rocket, launched December 2015, using newly developed furnace. A grain-refined Al–20 wt%Cu sample fully melted and solidified during 360 s microgravity sequence recorded time-resolved X-radiography. Equiaxed nucleation, dendritic growth, solutal impingement, eutectic transformation...

First-principles density-functional theory calculations for C solution enthalpies, ${H}^{\text{sol}}$, and diffusion activation ${H}^{\text{diff}}$, in body-centered-cubic Fe Cr are presented. The results compare well with experiments, provided that the effect of magnetic disordering is accounted for. Likewise, Cr, calculated ${H}^{\text{sol}}$ ${H}^{\text{diff}}$ agree available experiments. In both materials, deviation between enthalpies critically assessed experimental less than 0.05 eV....

Using molecular dynamics, we have studied the behaviour of cylindrical [001]-oriented Fe and FeCr nanowires under uniaxial tensile strain with both an embedded atom method (EAM) a Tersoff-like bond order potential. The mechanical properties were analysed deformation mechanism was compared between potentials. effects chromium content size wire studied. Both potentials show elongation by twinning in 〈111〉/{211} system resulting significantly stiffer stronger [110]-axial nanowire. pure iron are...

In this work, an interatomic potential for the beryllium–tungsten system is derived. It final piece of a puzzle, now containing all possible interactions between fusion reactor materials beryllium, tungsten and carbon as well plasma hydrogen isotopes. The suitable plasma–wall interaction simulations can describe intermetallic Be2W Be12W phases. energy Be surface W atom, vice versa, agrees qualitatively with ab initio calculations. also reasonably BexWy molecules x, y = 1, 2, 3, 4.

Using molecular dynamics simulations and the embedded atom method (EAM) potential we have investigated sputtered clusters produced by 15 keV xenon impacts on silver 20 gold. Ejected were simulated for long times, up to 0.01--1 \ensuremath{\mu}s, in order investigate fragmentation of nascent clusters. The size distributions final calculated fitted an inverse power law, resulting exponents close 2 3, depending range cluster sizes used. These values are agreement with other experiments. results...

Iron carbide (Fe3C), also known as cementite, is present in many steels and has been seen nanosized precipitates steels. We examine the interaction of edge dislocations with cementite Fe by molecular dynamics. The simulations are carried out a Tersoff-like bond order interatomic potential Henriksson et al. for Fe-C-Cr systems. Comparing results obtained this defect free system from previously used potentials, we find that gives significantly higher values critical stress, at least low...

We present an analytical bond-order potential for the Fe-O system, capable of reproducing basic properties wüstite as well energetics oxygen impurities in [Formula: see text]-iron. The predicts binding energies various small oxygen-vacancy clusters text]-iron good agreement with density functional theory results, and is therefore suitable simulations oxygen-based defects iron. apply stability structure Fe/FeO interfaces FeO precipitates iron, observe that shape can change due to formation...

Recent work on the sizes of craters produced by ion impacts solids has shown that size crater scales with inverse square cohesive energy. This observation is in contrast to macroscopic impacts, which scale directly It relied assumption melting temperature proportional Using computer simulations, we now show fact product and provides direct proof reason different behavior ion-induced cratering flow liquid ions.

Abstract The small‐amplitude conformational changes in macromolecules can be described by the bond lengths and angles. descriptors of large scale are torsions. We present a recursive algorithm, which vector is explicitly written terms these internal, or polyspherical coordinates, local frame defined two other vectors their cross product. Conformations linear branched molecules, as well molecules containing rings this way. orientation molecule body frame. It parametrized instantaneous...

The number of point defects formed in spherical cementite and Cr23C6 inclusions embedded into ferrite (α-iron) has been studied compared against cascades pure versions these materials (only ferrite, Fe3C, or a cell). Recoil energies between 100 eV 3 keV temperatures 400 K 1000 were used. overall tendency is that the — such as antisites, vacancy interstitials increases with recoil energy temperature. radial distributions indicate interface host tend to amplify restrict defect formation...