“…We note that the loops observed under mechanical deformation are mostly full dislocation loops. This differs from dislocation loops induced by radiation damage, which are mostly bound by partials, with the addition of some stair-rod dislocations bounding stacking fault tetrahedra (SFT) or SFT precursors 21 . Figure 7 Snapshots showing the stacking-fault planes (brown) and twin boundaries (pink) in elemental Fe and Ni and several random Fe Ni alloys at full indentation (left) and after retraction of the indenter (right).…”
Section: Resultsmentioning
confidence: 92%
“…Diffusion processes in Fe Ni random alloys were studied by Osetsky et al 18 using MD and kinetic Monte Carlo as an example of the sluggish diffusion in concentrated alloys 19 . The evolution of extended defects, such as dislocation loops, under irradiation was studied by experiment and MD 20 , 21 . The influence of stress on radiation-induced properties was studied by simulations in Ref.…”
We investigate by molecular dynamics simulation the mechanical behavior of concentrated alloys under nanoindentation for the special example of single-phase fcc Fe$$_{x}$$
x
Ni$$_{1-x}$$
1
-
x
alloys. The indentation hardness is maximum for the equiatomic alloy, $$x=0.5$$
x
=
0.5
. This finding is in agreement with experimental results on the strength of these alloys under uniaxial strain. We explain this finding with the increase of the unstable stacking fault energy in the alloys towards $$x=0.5$$
x
=
0.5
. With increasing Fe content, loop emission from the plastic zone under the indenter becomes less pronounced and the plastic zone features a larger fraction of screw dislocation segments; simultaneously, the length of the dislocation network and the number of atoms in the stacking faults generated in the plastic zone increase. However, the volume of twinned regions in the plastic zone is highest for the elemental solids and decreases for the alloys. This feature is explained by the fact that twinning proceeds by the glide of dislocations on adjacent parallel lattice planes; this concerted motion is less efficient in the alloys. Finally, we find that surface imprints show increasing pile-up heights with increasing Fe content. The present results will be of interest for hardness engineering or generating hardness profiles in concentrated alloys.
“…We note that the loops observed under mechanical deformation are mostly full dislocation loops. This differs from dislocation loops induced by radiation damage, which are mostly bound by partials, with the addition of some stair-rod dislocations bounding stacking fault tetrahedra (SFT) or SFT precursors 21 . Figure 7 Snapshots showing the stacking-fault planes (brown) and twin boundaries (pink) in elemental Fe and Ni and several random Fe Ni alloys at full indentation (left) and after retraction of the indenter (right).…”
Section: Resultsmentioning
confidence: 92%
“…Diffusion processes in Fe Ni random alloys were studied by Osetsky et al 18 using MD and kinetic Monte Carlo as an example of the sluggish diffusion in concentrated alloys 19 . The evolution of extended defects, such as dislocation loops, under irradiation was studied by experiment and MD 20 , 21 . The influence of stress on radiation-induced properties was studied by simulations in Ref.…”
We investigate by molecular dynamics simulation the mechanical behavior of concentrated alloys under nanoindentation for the special example of single-phase fcc Fe$$_{x}$$
x
Ni$$_{1-x}$$
1
-
x
alloys. The indentation hardness is maximum for the equiatomic alloy, $$x=0.5$$
x
=
0.5
. This finding is in agreement with experimental results on the strength of these alloys under uniaxial strain. We explain this finding with the increase of the unstable stacking fault energy in the alloys towards $$x=0.5$$
x
=
0.5
. With increasing Fe content, loop emission from the plastic zone under the indenter becomes less pronounced and the plastic zone features a larger fraction of screw dislocation segments; simultaneously, the length of the dislocation network and the number of atoms in the stacking faults generated in the plastic zone increase. However, the volume of twinned regions in the plastic zone is highest for the elemental solids and decreases for the alloys. This feature is explained by the fact that twinning proceeds by the glide of dislocations on adjacent parallel lattice planes; this concerted motion is less efficient in the alloys. Finally, we find that surface imprints show increasing pile-up heights with increasing Fe content. The present results will be of interest for hardness engineering or generating hardness profiles in concentrated alloys.
“…For the third condition, the thermostat temperature was adjusted to 100, 300, 500, 700, or 900 K, while keeping the PKA energy at 3 keV and the H concentration at 10,000 appm. The choice of each variable range in this work followed the general considerations from previous studies [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ], facilitating a comparative analysis. It should be noted that each case involved 10 independent MD simulations to ensure statistical validity.…”
Nickel-based alloys have demonstrated significant promise as structural materials for Gen-IV nuclear reactors. However, the understanding of the interaction mechanism between the defects resulting from displacement cascades and solute hydrogen during irradiation remains limited. This study aims to investigate the interaction between irradiation-induced point defects and solute hydrogen on nickel under diverse conditions using molecular dynamics simulations. In particular, the effects of solute hydrogen concentrations, cascade energies, and temperatures are explored. The results show a pronounced correlation between these defects and hydrogen atoms, which form clusters with varying hydrogen concentrations. With increasing the energy of a primary knock-on atom (PKA), the number of surviving self-interstitial atoms (SIAs) also increases. Notably, at low PKA energies, solute hydrogen atoms impede the clustering and formation of SIAs, while at high energies, they promote such clustering. The impact of low simulation temperatures on defects and hydrogen clustering is relatively minor. High temperature has a more obvious effect on the formation of clusters. This atomistic investigation offers valuable insights into the interaction between hydrogen and defects in irradiated environments, thereby informing material design considerations for next-generation nuclear reactors.
“…Binary alloy M (Fe, Co, and Ni)–Cr compounds, which serve as the material foundation for our design strategy, are renowned for their versatility. − Their success is based on the ability to create new materials using different combinations of alloys from the binary, − ternary, quaternary, and high entropy alloy families. This is achieved by following simple rules that consider the atom’s position, number of valence electrons, degree of atomic disorder, and strength of exchange interactions in the flexible structure.…”
Alloying antiferromagnetic Cr with ferromagnetic Ni forms an excellent starting point to design materials for various room temperature applications, such as spintronics, the magnetocaloric effect, and hyperthermia, thanks to its tunable Curie temperature, T C , and competing magnetic interactions. In this report, we present a comprehensive analysis of the relationships among film thickness, Cr surface segregation, and magnetic properties in nanocrystalline Ni 100−x Cr x (x = 5−15 at. %) thin films. We assess the impact of Cr segregation evolution on various magnetic transitions as the thickness and Cr doping level increase. These films exhibited ferromagnetic to paramagnetic transitions at higher temperatures and ferromagnetic to spin-glass transitions at low temperatures, which resulted in a phase diagram that differed from the bulk equilibrium phase diagram. Further, magnetometry and magnetic force microscopy were performed to investigate the magnetic anisotropy and magnetic domain structure as a function of film thickness. It is found that the perpendicular component of magnetic anisotropyled to a stripe domain structure in films with critical thicknesses above 20 nm. Substantial changes in the magnetization behavior of nanocrystalline Ni 100−x Cr x thin films within a few Cr at. % doping provide a means for adjusting both soft and hard magnetic component applications.
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