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Nickel-based alloys have demonstrated significant promise as structural materials for Gen-IV nuclear reactors. However, the understanding of the interaction mechanism between the defects resulting from displacement cascades and solute hydrogen during irradiation remains limited. This study aims to investigate the interaction between irradiation-induced point defects and solute hydrogen on nickel under diverse conditions using molecular dynamics simulations. In particular, the effects of solute hydrogen concentrations, cascade energies, and temperatures are explored. The results show a pronounced correlation between these defects and hydrogen atoms, which form clusters with varying hydrogen concentrations. With increasing the energy of a primary knock-on atom (PKA), the number of surviving self-interstitial atoms (SIAs) also increases. Notably, at low PKA energies, solute hydrogen atoms impede the clustering and formation of SIAs, while at high energies, they promote such clustering. The impact of low simulation temperatures on defects and hydrogen clustering is relatively minor. High temperature has a more obvious effect on the formation of clusters. This atomistic investigation offers valuable insights into the interaction between hydrogen and defects in irradiated environments, thereby informing material design considerations for next-generation nuclear reactors. [ABSTRACT FROM AUTHOR]

α‐type Ti35 alloy (Ti‐6 wt%Ta) has been recommended as one of the candidate materials for advanced nuclear reactors due to its excellent overall performance. Nonetheless, irradiation effects on the alloy remain scarcely understood by far. Herein, the primary irradiation damage of Ti35 alloy is investigated from multiple perspectives using atomistic simulations. Results show that with the increasing energy of the primary knock‐on atom (2 keV ≤ EPKA ≤ 10 keV), the number of Frenkel pairs (NFP) gradually increases independent of the incident direction of PKA (IDPKA) and the ambient temperature (100 K ≤ T ≤ 700 K), while it exhibits a downtrend at each IDPKA as the T elevates. The magnitude of EPKA can affect the anisotropy of IDPKA on irradiation damage. Unrelated to EPKA, IDPKA, and T, di‐interstitial clusters and Nvacancy > 3 clusters respectively account for the largest proportion of their categories, highlighting their stability. In any case, vacancies are more prone to cluster than interstitials. The increase of EPKA has a greater effect on vacancy clustering than interstitial clustering but can promote the increase in both the clustering fractions. An important insight into the understanding of the irradiation damage behaviors for the alloy has been provided. [ABSTRACT FROM AUTHOR]

[Display omitted] In the biological environment, mineral crystals exquisitely controlled by biomacromolecules often show intricate hierarchical structures and superior mechanical properties. Among these biominerals, spicules, hybrid silica/protein superstructures serving as skeletal elements in demosponges, represent an excellent example for motivating the synthesis of silica materials. Herein, by designing sequence-defined peptoids containing side chains with a strong binding to silica, we demonstrated that self-assembly of these peptoids into fiber structures enables the mimicking of both biocatalytic and templating functions of silicatein filaments for the formation of silica fibers at near-neutral pH and ambient temperature. We further showed that the presence of amino groups is significant for the nucleation of silica on self-assembled peptoid nanofibers. Molecular dynamics simulation further confirmed that having silica-binding of amino side chains is critical for self-assembled peptoid fibers in triggering silica formation. We demonstrated that tuning inter-peptoid interactions by varying carboxyl and amino side chains significantly influences the assembly kinetics and final morphologies of peptoid assemblies as scaffolds for directing silica mineralization to form silica spheres, fibers, and sheets. The formation of silica shell on peptoid fibers increased the mechanical property of peptoid hydrogel materials by nearly 1000-fold, highlighting the great potential of using silicification to enhance the mechanical property of hydrogel materials for applications including tissue engineering. Since peptoids are highly robust and programmable, we expect that self-assembly of peptoids containing solid-binding side chains into hierarchical materials opens new opportunities in the design and synthesis of highly tunable scaffolds that direct the formation of composite nanomaterials. [ABSTRACT FROM AUTHOR]

Cu−diamond composites have been proposed as a candidate thermal management material for spacecraft electronics. Nevertheless, irradiation effects on the composites remain poorly understood at present. Here we focus on investigating the influence of Cu−diamond interfaces (CDIs) on energetic displacement cascades using atomistic simulations. Results show that a primary knock-on atom of Cu (PKA-Cu) can induce more significant damage than a PKA-C. Under almost all circumstances, the statistically averaged fraction of surviving interstitials is not only lower than that of vacancies but also no more than 1. Because of the unique nature in the mobility and interactions with CDIs, Cu interstitials exhibit the lowest concentration among all defects in most cases. The high residual rate of displaced defects in diamond makes it relatively difficult to heal. The structural damage is mainly manifested in a short-range disorder of diamond and a long-range disorder of Cu after irradiation. At elevated temperatures, the atomic displacement region may form compact chain-like defects to restrain lattice loosening. Despite the above, CDIs could act as effective sinks to facilitate the recombination and/or annihilation of irradiation-induced defects in all scenarios. This study provides an important insight into the understanding of the microscopic evolution of irradiation defects for the composites. [ABSTRACT FROM AUTHOR]

Ti35 alloy (Ti-6wt.%Ta) has greatly promising applications in nuclear industries due to its excellent overall performance. Nevertheless, atomistic mechanisms of its defect clustering evolution due to long-term exposure to irradiation remain scarcely understood by far. Here we investigate the heavy irradiation damage in Ti35 alloy with a dose of up to 4.0 canonical displacement per atom (cDPA) using atomistic simulations of Frenkel pair accumulation. Results show that defect clustering becomes remarkable before 0.04 cDPA and thereafter tends to be relatively stable, and the fraction is not directly dependent on the irradiation dose. Interstitials exhibit a stronger ability than vacancies to form clusters and especially the N int >5 clusters may cause the formation of 1/3<1‾210> dislocation loops. Compared to the matrix, N int ≤5 interstitial-type defects show a depletion of Ta atoms, while N int >5 clusters are Ta-rich. This study provides an important insight into the understanding of the irradiation damage behaviors for Ti35 alloy. • A heavily irradiated Ti35 alloy with a dose of 4 cDPA is studied using FPA methods. • Defect clustering fraction is almost not dependent on the irradiation dose. • Interstitials exhibit a stronger ability than vacancies to form clusters. • Clustering causes the formation of 1/3<1‾210> interstitial-type dislocation loops. • Low-order clusters show a depletion of Ta while high-order clusters are Ta-rich. [ABSTRACT FROM AUTHOR]