The microstructural evolution of a HfNbTaTiZr high-entropy alloy subjected to cold rolling and subsequent annealing was investigated. The dislocation activity dominates the deformation process. The microstuctural evolution of the alloy during cold rolling can be described as follows: (i) formation of dislocation tangles, (ii) formation of microbands, (iii) formation of thin laths and microshear bands containing thin laths, (iv) the transverse breakdown of the lath to elongated segment, and (v) formation of fine grains. During annealing at 800 and 1000 °C, decomposition of the metastable high-temperature body-centered cubic phase proceeded through a phase separation reaction. Annealing at 800 °C resulted in a nonrecrystallized microstructure with abundant second-phase particles distributed randomly. The second-phase particles with an average size of ∼145 nm were enriched in Ta and Nb, while the chemical composition of the matrix was close to the average composition of the alloy. Meanwhile, an unknown phase slightly enriched in Hf, Zr, and Ti was detected in the interfacial region between the second-phase particles.

The solid–liquid interfacial free energy of silicon was calculated by the method based on classical nucleation theory (CNT), where the molecular dynamic (MD) simulations were carried out, and a series of cylindrical solid nuclei were equilibrated with undercooled liquid phase to create an ideal model of a homogeneous nucleation. The interfacial free energy was extracted from the relationship between the critical nuclei radii and their corresponding equilibrium temperatures. The influence of the interfacial curvature on its free energy was for the first time considered in our work, the influence can be measured by a Tolman length which was introduced to modify the traditional CNT; therefore, more accurate results were obtained. The averaged melting point and Tolman length extracted from simulations were 1678.27 K and 2.82 Å, respectively, which are consistent with the expected results. The averaged interfacial free energy is 401.92 mJ/m2, which is in good agreement with the results from experiments.

Protein cage based nanoarchitectures hold great potential in the fields of energy, catalysis, and bio-applications owing to their ability to tune material’s properties in a benign biomimetic approach. We demonstrate the self-assembly of bacteriophage P22 using inorganic nanoparticles and dendrimers for the first time. Inorganic nanoparticles (iron oxide, CoFe2O4, and Au) and polyamidoamine serve as model systems for rigid and soft linker materials, respectively, to induce P22 assembly via electrostatic interaction. We observed distinctly different packing of P22 using nanoparticles as compared to the polyamidoamine polymer. Notably, the ratio of nanoparticle: P22 and ligand packing on the nanoparticle surface are dominant controls for this assembly. The best results are obtained at 6.5:1 nanoparticle:P22 number ratio in the presence of 50 mM NaCl, pH = 6. In contrast, dense area assembly of P22 is observed at 8:1 polyamidoamine:P22 number ratio with 1 M NaCl (pH ∼ 7.5) for the dendrimer.

Thermal transport in materials used for energy applications is a physical process directly tied to performance and reliability. As a result, a great deal of effort has been devoted to understanding thermal transport in materials whose ability to conduct heat is critical. Here, our objective is to discuss the utility of laser-based thermoreflectance (TR) approaches that provide microscale measurement of thermal transport. We provide several examples that implement the TR technique to investigate thermal transport in materials used in nuclear energy applications. First, we discuss utility of this technique to measure thermal conductivity in ion irradiated ceramic materials during investigations where the primary objective is to understand the impact of radiation induced crystalline structure defects on thermal transport. We also present the capability of TR approach to resolve thermal conductivity of each layer in tristructural isotropic fuel, silicon carbide fiber composites, and 2nd phase precipitates in uranium silicide. Finally, the ability to measure interface thermal resistance between adjacent layers in composites is demonstrated.

The rapid growth of scientific publications necessitates new methods to understand the direction of scientific research within fields of study, ascertain the importance of particular groups, authors, or institutions, compute metrics that can determine the importance (centrality) of particular seminal papers, and provide insight into the social (collaboration) networks that are present. We present one such method based on analysis of citation networks, using the freely available CiteSpace Program. We use citation network analysis on three examples, including a single material that has been widely explored in the last decade (BiFeO3), two small subfields with a minimal number of authors (flexoelectricity and Kitaev physics), and a much wider field with thousands of publications pertaining to a single technique (scanning tunneling microscopy). Interpretation of the analysis and key insights into the fields, such as whether the fields are experiencing resurgence or stagnation, are discussed, and author or collaboration networks that are prominent are determined. Such methods represent a paradigm shift in our way of dealing with the large volume of scientific publications and could change the way literature searches and reviews are conducted, as well as how the impact of specific work is assessed.

The origin of ionic conductivity in bulk lithium lanthanum titanate, a promising solid electrolyte for Li-ion batteries, has long been under debate, with experiments showing lower conductivity than predictions. Using first-principles-based calculations, we find that experimentally observed type I boundaries are more stable compared with the type II grain boundaries, consistent with their observed relative abundance. Grain boundary stability appears to strongly anti-correlate with the field strength as well as the spatial extent of the space charge region. Ion migration is faster along type II grain boundaries than across, consistent with recent experiments of increased conductivity when type II densities were increased.

Ultrafast laser processing can be used to realize various morphological surface transformations, ranging from direct contour shaping to large-area-surface functionalization via the generation of “self-ordered” micro- and nanostructures as well as their hierarchical hybrids. Irradiation with high-intensity laser pulses excites materials into extreme conditions, which then return to equilibrium through these unique surface transformations. In combination with suitable top-down or bottom-up manufacturing strategies, such laser-tailored surface morphologies open up new avenues toward the control of optical, chemical, and mechanical surface properties, featuring various technical applications especially in the fields of photovoltaics, tribology, and medicine. This article reviews recent efforts in the fundamental understanding of the formation of laser-induced surface micro- and nanostructures and discusses some of their emerging capabilities.

This article summarizes recent research on laser-based processing of two-dimensional (2D) atomic layered materials, including graphene and transition-metal dichalcogenides (TMDCs). Ultrafast lasers offer unique processing routes that take advantage of distinct interaction mechanisms with 2D materials to enable extremely localized energy deposition. Experiments have shown that ablative direct patterning of graphene by ultrafast lasers can achieve resolutions of tens of nanometers, as well as single-step pattern transfer. Ultrafast lasers also induce non-thermal excitation mechanisms that are useful for the thinning of TMDCs to tune the 2D material bandgap. Laser-assisted site-specific doping was recently demonstrated and ultrafast laser radiation under ambient air environment could be used for the direct writing of high-quality graphene patterns on insulating substrates. This article concludes with an outlook on developing further advanced laser processing with scalability, in situ monitoring strategies, and potential applications.