Irradiation dose-dependent mechanical response of titanium through point defect accumulation

YM Qi and CP Zhang and TW He and H Xie and M Zhao and ML Feng, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 569, 165899 (2025).

DOI: 10.1016/j.nimb.2025.165899

Titanium and its alloys are key structural materials for nuclear reactors, where radiation tolerance is essential. Understanding how irradiation-induced defects, particularly their spatial distribution, affect mechanical properties is crucial for developing radiation- resistant materials. In particular, spatial randomness of defects has been shown to significantly influence irradiation hardening during early exposure stages, highlighting the need to establish a clear link between defect distribution characteristics and strengthening mechanisms. In this study, molecular dynamics simulations are conducted to emulate multiple low-dose irradiation scenarios. The resulting irradiation- induced defects are statistically characterized in terms of their size, atomic structure, and spatial distribution. Based on these statistical features, a stochastic Peierls-Nabarro (PN) model is developed to investigate how random spatial fluctuations in defect distributions contribute to irradiation-induced hardening. To further validate these findings, equivalent dislocation slip simulations are performed to qualitatively assess the impact of spatially distributed defects on dislocation mobility and thus on yield strength. This work provides atomic-scale insights into the evolution of defect density and spatial configuration under low-dose irradiation and clarifies their role in influencing irradiation hardening in titanium-based materials. The results not only deepen our understanding of defect-mechanical property relationships but also offer valuable guidance for the design of next- generation irradiation-tolerant materials.

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