Effects of chemical alternation on damage accumulation in concentrated solid-solution alloys

Abstract

Single-phase concentrated solid-solution alloys (SP-CSAs) have recently gained unprecedented attention due to their promising properties. To understand effects of alloying elements on irradiation-induced defect production, recombination and evolution, an integrated study of ion irradiation, ion beam analysis and atomistic simulations are carried out on a unique set of model crystals with increasing chemical complexity, from pure Ni to Ni80Fe20, Ni50Fe50, and Ni80Cr20 binaries, and to a more complex Ni40Fe40Cr20 alloy. Both experimental and simulation results suggest that the binary and ternary alloys exhibit higher radiation resistance than elemental Ni. The modeling work predicts that Ni40Fe40Cr20 has the best radiation tolerance, with the number of surviving Frenkel pairs being factors of 2.0 and 1.4 lower than pure Ni and the 80:20 binary alloys, respectively. While the reduced defect mobility in SP-CSAs is identified as a general mechanism leading to slower growth of large defect clusters, the effect of specific alloying elements on suppression of damage accumulation is clearly demonstrated. This work suggests that concentrated solid-solution provides an effective way to enhance radiation tolerance by creating elemental alternation at the atomic level. The demonstrated chemical effects on defect dynamics may inspire new design principles of radiation-tolerant structural alloys for advanced energy systems.

On the role of heterogeneity in concentrated solid-solution alloys in enhancing their irradiation resistance

“…As such, the trend of defect number simulated is comparable to the damage accumulation observed in experiments. The results indicate similar defect evolution between Ni 0.5 Fe 0.5 and Ni 0.8 Cr 0.2 , which is consistent with experimental results [25]. In addition, the lowest defect number in Ni 0.4 Fe 0.4 Cr 0.2 and Ni 0.333 Co 0.333 Cr 0.333 is also in accordance with the available experiments [8,26] 333 , yet the defect evolution in these three alloys is similar.…”

“…However, the original version of the Cr potential leads to instabilities in alloys, and slight modification was made based on the analysis of Anand et al [30]. These potentials have been successfully used to model damage evolution in corresponding alloys previously [8,10,21,24,25].…”

Delayed damage accumulation by athermal suppression of defect production in concentrated solid solution alloys

“…In order to evaluate qualitatively the evolution of the relative disorder resulting from the Ar-ion irradiation, disorder profiles were extracted from the analysis of RBS/C spectra (these spectra are plotted in Figure S1 of the supplementary material) using an iterative procedure [41], which has been previously used to analyze ion-irradiated SP-CSAs at RT [18,19] and validated in some recent molecular dynamics simulations [42,43]. The obtained disorder profiles for Ar-irradiated Ni (red circles) are illustrated in Figure 1 and compared with those for Arirradiated NiFe (blue triangles) and NiFeCoCr (green squares) single crystals.…”

“…nuclear reactor applications), a combination of these improvements is highly desirable, and exploiting the extreme chemical disorder of concentrated alloys may provide a new paradigm for designing structural materials for next-generation nuclear power systems. Over the past few years, pioneering efforts have been devoted to the fundamental understanding of radiation defects in SP-CSAs, mimicking the radiation produced in nuclear reactors using external irradiations with various types of heavy ions at room temperature (RT) [14][15][16][17][18][19] and high temperatures (HT) [20][21][22][23][24][25][26]. The results of these studies have demonstrated that increasing chemical complexity strongly enhances the radiation resistance of these alloys, which has been attributed to sluggish diffusion [27][28][29] and enhanced dynamic annealing of simple defects at early stages during irradiations at RT and HT [2,15,23].…”

“…Rutherford backscattering spectrometry in channeling conditions (RBS/C) is frequently employed to quantitatively determine depth profiles of disorder in ion-irradiated single crystals. Recently, we have utilized RBS/C to profile irradiation-induced damage evolution in SP-CSAs at RT [14][15][16][17][18][19]. The detection limit of the disorder is expected to be enhanced at cryogenic temperatures due to the reduction of thermal vibrations [30,31].…”