Differences in the accumulation of ion-beam damage in Ni and NiFe explained by atomistic simulations

Abstract

Following low-dose irradiation with a 3 MeV beam of Au ions, i.e. less than one displacement per atom, a lower number of defects were experimentally observed in NiFe than in pure Ni. At higher doses, more damage is observed in NiFe than in pure Ni. Also, at these high doses, defect structures are observed deep in the material, far from the region where ions are implanted, more so in Ni than in NiFe. In this study, these experimental results are explained using atomistic modeling. Sequences of overlapping displacement cascades with intervening defect aging are simulated. Evidence is provided that nanosecond aging at 900K can be used as a surrogate for long-time, room-temperature aging. Then, using this procedure, it is shown that the low defect diffusivity of NiFe leads to less aggregation and recombination events between each displacement cascade in a given volume than in Ni. Variations in the local defect chemistry in NiFe produces a broad spectrum of defect formation energy, leading to the trapping of defects at energetically favorable sites: this explains the low defect diffusivity. Also, this low diffusivity explains why, at high dose, defects in NiFe do not propagate as deeply in the material than in pure Ni.

The effect of alloying nickel with iron on the supersonic ballistic stage of high energy displacement cascades

“…If this is the case, one might be able to tune alloy composition to enhance such primary damage reduction at the high end of the PKA spectrum. Likewise, the kinetic evolution of the microstructure created by the cascade on longer timescales has an important effect on defect cluster size [5]. These issues certainly warrants further investigation.…”

“…These alloys possess a simple face centered cubic structure (fcc), but are made of several principle elements (such as NiFeCoCrMn), in contrast with conventional alloys that typically contain only one principle component. This high chemical complexity was shown to reduce electronic [2,3] and phonon [4] mean free paths, as well as slow down defect mobility [5,6]. While these properties are known to be important for radiation damage evolution, the mechanisms that explain energy dissipation and defect production in these systems remain largely unexplored.…”

Bimetallic zeolitic imidazolate frameworks-derived porous carbon-based materials with efficient synergistic microwave absorption properties: the role of calcining temperature

“…As shown in Fig. 8b 1 , the yellow area in the twodimensional contour map is considered as the effective absorption area. The composite of Co@pNGC-600 can achieve an effective absorption at 3.0-17.8 GHz by adjusting the coating thickness in the range of 2.0-5.5 mm.…”

“…In everyday life, radiation will not only interfere with the normal operation of the electronic equipment but also produce a great threat to the ecological environment and human health. 1,2 Furthermore, in the military environment, the radar detection technology causes a serious threat to the abilities of survivability and penetration of military targets. The application of EM absorption materials is a wise and effective method to avoid the acquisition of radar and achieve a stealth mode.…”

Phase stability and microstructures of high entropy alloys ion irradiated to high doses

“…Moreover, the molecular dynamics (MD) simulations [32,38,39] also show that the mobility of defects is lower in multi-component solid solution than in pure metals, and the formation of large extended defects is suppressed in multi-component disordered solid solution alloys. Jin et al [40] has also shown that the volume swelling is reduced with increasing the number elements in disordered solid solution, which hints that the volume swelling is closely related to the entropy of mixing of the solid solution.…”