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The behavior of solute atoms in an undersaturated Fe-3.3 at.%Ni model alloy upon heavy and light particle irradiations was investigated by Atom Probe Tomography. Whereas first irradiations, performed using 27 MeV Fe ions at 400 °C, highlight significant Ni enrichment on point defect clusters, solute-rich features detected after 2.8 MeV H + ion (400 °C) and 1 MeV electron (320 °C) irradiations are only associated with pre-existent microstructural defects. Nanoindentation tests show no hardening in light particle irradiated samples, strongly suggesting that no dislocation loop formed. These observations put forward the importance of point defect clusters resulting from displacement cascades in Ni clusters' formation. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In situ irradiation in transmission electron microscope following pre-irradiation was performed on Fe-0.6Ni alloy to investigate the growth of dislocation loops under irradiation. The observations showed two types of loop growth behaviour. One type was almost linear growth with irradiation dose, possibly caused by loop absorbing freely migrating defects. The other was abrupt growth with rapid increase in diameter. It was found that nanometre-sized loop might migrate one-dimensionally, following which the large loop could absorb the small loop. This process can result in the abrupt growth of loop and broadening of loop size distribution. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The irradiation of high-energy particles always leads to the embrittlement of metallic materials. Here, we report an abnormal irradiation toughening phenomenon in a hierarchical structured ZrTi, which results from the irradiation-induced lattice relaxation that yields an enhanced ductility with a slight decrease of strength. Positron annihilation measurements reveal that the lattice relaxation dominantly originates from a recombination of irradiation-induced interstitials (i.e., Ti atoms) with preexisting dislocation-associated vacancies. This study provides an approach to suppress the irradiation-induced brittleness in metallic materials. [ABSTRACT FROM AUTHOR]