A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. The results suggest design criteria for next generation radiation tolerant structural alloys.

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The energetics and kinetics regarding helium (He) cluster growth in bcc tungsten (W) are unveiled using combined techniques of molecular statics and molecular dynamics. The principal mechanisms accounting for the decrease of system potential energy are identified to be trap mutation, 100 → 1/2 111 cluster transformation, loop punching, coalescence between 1/2[1 1-1] and 1/2[1-1-1] loops, and loop capturing. The kinetic barriers associated with these key atomistic events are estimated. This work provides new insights into the complex yet intriguing atomistic evolution sequence of the He cluster and interstitial loop in W-based nuclear fusion materials under irradiation.

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The shear modulus and damping ratio are two important index in equivalent nonlinear model which is widely used in seismic response analysis. GDS resonant-column is used to study the shear modulus and damping ratio of highly weathered granite by controlling the consolidation confining pressure and pore water pressure. Variation of resonant frequency, shear modulus and damping ratio can be observed when different effective stress which is changed with confining pressure and pore water pressure applied on the sample. Hadin-Drnevich fitting curves are given on the basis of experimental data, and damping mechanism of highly weathered granite is discussed by making use of frictional theory. We can conclude from the results that there is a positive correlation between resonance frequency and shear strain, while there is a negative correlation between samples damping ratio and shear strain. The effective stress impact both samples shear modulus and damping ratio. However, pore water pressure can only act on damping ratio.

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Metallic additives, Al nanoparticles in particular, have extensively been used in energetic materials (EMs), of which thermal decomposition is one of the most basic properties. Nevertheless, the underlying mechanism for the highly active Al nanoparticles and their oxidized counterparts, the Al2O3 nanoparticles, influencing the thermal decay of aluminized EMs has not fully been understood. Herein, we explore the influence of Al and Al2O3 nanoparticles on the thermal decomposition of 1,3,5trinitro-1,3,5-triazinane (RDX), one of the most common EMs, based on large-scale reactive force field molecular dynamics simulations within three heating schemes (constant-temperature, programmed and adiabatic heating). The presence of Al nanoparticles significantly reduces the induction time and energy required to activate the RDX decay, and greatly increases energy release. The fundamental reason for these results is that Al changes the primary decay pathway from the unimolecular N-NO2 scission of RDX to bimolecular barrier-free or low-barrier Al-involved reactions, and possesses a strong O-extraction capability and a moderate one to react with C/H/N. It is also responsible for the growth of the Al-contained clusters. And Al2O3 nanoparticles can also demonstrate such catalysis capability but contribute less to the enhancement of energy release. Moreover, the detailed evolutions of key thermodynamic properties, intermediate and final gaseous products, and Al-contained products are also presented. Besides, under the programmed heating and adiabatic heating conditions the catalysis of the Al and Al2O3 nanoparticles becomes more distinct. Thereby, many properties of aluminized EMs are expected to well be understood by our simulation results.

It has become increasingly important to add Al nanoparticles (ANPs) into energetic materials (EMs) to overcome the issue of Al particles aggregation and promote the efficiency of heat release. Nevertheless, the underlying mechanism for the role of ANPs in EMs still remains limited. By means of reactive molecular dynamics simulations with the ReaxFF potential, the present work focuses upon the evolution of ANPs in a hot EM of 2,4,6-trinitro-1,3,5-triaminobenzene (TATB), which features very high insensitivity and O-lack. As a whole, adding ANPs unexceptionally increases heat release, and the morphological evolution of ANPs significantly depends on their sizes and contents, as the smaller size and the smaller content facilitate microexplosion. Moreover, a cracking of the core–shell structured Al@Al2O3 is observed in the hot TATB, as in oxygen. Besides Al–O bonds, Al–C and Al–N bonds are formed owing to the O-poor character of TATB. In addition, fusion of four ANPs in a model is observed as the reaction proceeds. A hollow alumina sphere is formed when adding an Al@Al2O3 particle to hot TATB, and it is found that there is an inward O transport and more O atoms concentrated around the center of an ANP with a relatively large size and high content. This work is expected to deepen insight into the complex reaction mechanism of ANPs-containing EMs.