Radiation-induced segregation in multicomponent alloys: Effect of particle type

Abstract

The problem of irradiation-assisted stress-corrosion cracking (IASCC) in reactor cores is currently being addressed using different types of particle irradiation (electrons, protons, and heavy ions) to study the effect of neutron damage. The effect of radiation damage of greatest interest to the IASCC problem is the segregation of impurities or redistribution of alloying elements in the vicinity of the grain boundary. Differences among the types of irradiation include particle type, temperature, dose, and dose rate. The different particle type results in different "effective" displacement rates due to fundamental differences in the radiation damage state. The effect of displacement efficiency is incorporated into existing models for radiation-induced segregation and compared with experimentally determined values. Comparisons between theory and experiment were made using neutron-, proton-, and ion-irradiated stainless steels. Results showed that the measured chromium depletion prohle is generally narrower and shallower than that calculated from theory. Agreement between experiment and model was better in almost all cases when the particle efficiency was taken into account. Agreement was best for proton-irradiated steels, and less so for neutron and heavy ion-irradiated steels. The origins of this difference are probably due to spatial and depth resolution of the scanning transmission electron microscopy and Auger electron spectrometry measurement techniques, respectively, the lack of knowledge of the material parameters in modeling, and the uncertainty in the true displacement rate. Nevertheless, beyond 2 nm from the grain boundary, the shape of the experimental and calculated profiles agree reasonably well.

The Mechanism of Zr and Hf in Reducing Radiation-Induced Segregation in 316 Stainless Steel

“…Although not the primary cause, [1] grain-boundary (GB) RIS in these austenitic stainless steels may play some role in irradiation-assisted stress corrosion cracking (IASCC). [2][3][4] Enhancing point defect recombination would help to reduce RIS and improve material performance under irradiation. The addition of oversized solute elements is a strategy for reducing RIS in austenitic alloys.…”

Irradiation induced changes in small angle grain boundaries in mosaic Cu thin films

“…According to the SRIM program, the displacements per atoms (DPA) created in the Cu film is about 10 without considering defect recovery when the Cu film is subjected to a 200 keV He ion irradiation with a fluence of 5 × 10 17 ions/cm 2 . The fraction of point defects that are freely migrating after the quench stage is 0.02 [26,27]. Although this value is taken without considering the annealing stage involving further rearrangement and interaction of defects, the concentration of survived mobile interstitial (C r ) will be still much higher than the equilibrium interstitial concentration, as schematically shown in Fig.…”

Deterioration in coercivities of Fe–Pt and Co–Pt thin film magnets by ion irradiations

“…Cascade volume increases with increasing mean energy transferred to the PKA [19], and most of the displaced atoms recombine with vacant lattice sites during the subsequent cascade cooling phase [12]. It is presumed that recombination probability increases with an increase in the number of the crowded Frenkel pairs.…”