Atomic mixing by replacement collision sequences and other cascade effects is well known to create chemical disorder in irradiated alloys. Most studies of irradiation-induced disordering have focused on ex situ analysis of irradiated samples; however, fast in situ techniques are necessary to measure disordering at elevated temperatures without significant interference from concurrent re-ordering processes. In the present work, we use in situ electron diffraction with high speed data collection to measure the initial change in the long-range order parameter S with ion dose ϕ during 500 keV Ne+ irradiation of Cu3Au foils. The data reveal an unexpected and dramatic increase in the disordering rate as the critical order–disorder transition temperature TC is approached. Molecular dynamics simulations show that this increase is not due to temperature-dependent cascade mixing. We attribute the enhanced disordering, instead, to coupling between point defect fluxes and the chemical state of order.

To prepare high quality large solidified Al2O3/ZrO2 eutectic ceramic, the preparation processing of the presintered ceramic as a feed rod was investigated via experiments; some parameters of the induction heating zone process were optimized via numerical modeling; an Al2O3/ZrO2 eutectic ceramic rod with a diameter 10 mm was prepared. The results show that increasing the sintering temperature could increase the presintered ceramic’s bulk density, while increasing sintering time had little effect. And the bulk density increased first and then decreased with the molding pressure increase. And the saucer coil obtained a higher temperature gradient than the tubbiness coil for a fixed crucible wall maximum temperature, and the coil turn’s increase could increase the melting zone height in the induction zone melting process. In the directionally solidified Al2O3/ZrO2 eutectic ceramics, Al2O3 phase is the matrix phase, and the ZrO2 phase embedded in the Al2O3 phase mostly with the rod shape, and little with lamellar. The hardness of directionally solidified eutectic ceramics reaches 16.17 GPa and the fracture toughness reaches 4.76 MPa m1/2, which are 1.7 times and 1.5 times of the presintered eutectic ceramic, respectively.

The hot deformation behavior and processing characteristics of Mg–3Zn–0.3Ca–0.4La (wt%) alloys were investigated by hot compression deformation. The results suggested that deformation parameters had significant effects on deformation behavior and dynamic recrystallization of the Mg–Zn–Ca–La alloy. The average activation energy of deformation was calculated to be 188.9 kJ/mol. The processing map was constructed and analyzed based on the dynamic material model, and the optimum hot working window of the alloy was determined to be the temperature of 350 °C and the strain rates between 0.001 and 0.01 s−1. Furthermore, the DRX kinetic model of the Mg–3Zn–0.3Ca–0.4La (wt%) alloy was established, which implied that incomplete dynamic recrystallization occurred for the Mg–Zn–Ca–La alloy in the present work. Microstructure analysis indicated that deformation parameters played a critical role on the microstructure optimization. The dynamically recrystallized (DRXed) region fraction and the DRXed grain size were increased with the increase of deformation temperature and decrease of deformation rates.

To increase the corrosion prevention of stainless steel implant and fast recovery due to new bone-cell formation at the orthopedic implant site, in the present investigation, a trilayered (with bioceramic interlayer sandwiched between innermost passivated surface and outermost polymer coating) 316L stainless steel (SS) implant was designed and investigated. It was inferred that this new designed implant invokes faster and more bone-cell formation than uncoated commercially available 316L SS implants. Faster bone-cell formation at the coated implant site reduces the initial threat of implant corrosion. The electrochemical corrosion study proved that this model of coated implants is able to prevent corrosion up to 90% better than uncoated commercially available 316L SS. Subsequently, preclinical studies in the rabbit bone defect model (which included histology, radiology, fluorochrome labeling, push-out test, and scanning electron microscopy taken after 45 and 90 days) proved higher rate of new bone tissue formation and better push-out strength between tissue in contact and the coated implant. The toxicological study of vital organs like liver, kidney, and heart also exhibited no abnormality. The outcome of the experimentations indicates suitability of this trilayered 316L SS implant for bone repair and healing.

Uniformly dispersed ultra-small hollow Co9S8 nanoparticles (<10 nm) (H-Co9S8@C) and solid Co9S8 nanoparticles (S-Co9S8@C) in porous carbon were fabricated separately by solvothermal and sulfur powder sulphurisation using Co-MOF-74 as the template. Owing to significant structural stability and uniform hollow structure of carbon-encapsulated Co9S8, the as-prepared H-Co9S8@C exhibited excellent lithium ion storage performance as an anode material. Worked in the voltage of 0.01–3.0 V, H-Co9S8@C revealed outstanding rate capability (850, 670, 613, 552, 457, and 347 mA h/g at 0.1, 0.2, 0.5, 1, 2, and 3 A/g, respectively), and high reversible capacity (after 250 cycles with a remained capacity of 900.5 mA h/g). Compared with S-Co9S8@C, over 50 cycles, the discharge specific capacity of H-Co9S8@C was still maintained at 655 mA h/g at a current density of 0.5 A/g, whereas the capacity of S-Co9S8@C declined rapidly to 160.4 mA h/g. The results showed that superior capacity, excellent rate performance, and highly stable cycle performance depended mainly on the hollow characteristic of Co9S8.

The topological insulator/superconductor heterostructure is one of the most promising platforms to create and manipulate Majorana bound states. Here, we used molecular beam epitaxy to grow high-quality (Bi0.5Sb0.5)2Te3 films on Nb surfaces. To promote proper (Bi0.5Sb0.5)2Te3 film nucleation in the early growth stage, we developed a two-step growth method. Bi, Sb, and Te clusters were first evaporated at a low temperature of 180 °C, which is below the typical growth temperature and then annealed to form a crystalized passivation layer. Second, a standard (Bi0.5Sb0.5)2Te3 film was grown under the normal deposition temperature of 280 °C. We used reflection high-energy electron diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction to further characterize the (Bi0.5Sb0.5)2Te3 film and passivation layer quality. Finally, the top Nb film was laid down by magnetron sputtering at room temperature. The hetero-Nb/epitaxial (Bi0.5Sb0.5)2Te3/Nb stacks were further fabricated into micro-Josephson junctions and showed clear Josephson currents demonstrating an excellent material quality.

Because of rapid solidification involved in the laser or e-beam based additive manufacturing (AM) process, solution treatable metallic parts made by these methods usually possess a unique nonequilibrium microstructure which changes significantly during subsequent thermal treatment. Such evolution alters the size, morphology, length scale, and distribution of microstructural features and has a substantial impact on thermal properties and possibly on electrical properties as well. This study focuses on effects of microstructural evolution on thermal properties of an additively manufactured AlSi10Mg part. The changes of thermal properties such as thermal expansion, heat capacity, thermal diffusivity, and thermal conductivity as a function of thermal treatment are reported. The results show that the formation of supersaturated primary α aluminum and unique cellular structure imparted by fast solidification in the AM process are the major cause for the low thermal diffusivity and low thermal conductivity observed in this solution treatable, as-built part. A correlation between microstructural evolution and changes in thermal properties is established. Advantages and tailoring of the thermal properties of additively built parts are discussed. Implications of these results are important for other additively manufactured components based on popular solution treatable alloys.

Multi-pass warm rolling with falling temperature was proposed and investigated to obtain AZ31 Mg alloy sheets with a fine-grained microstructure. The results indicated that the grain microstructure of AZ31 alloy sheets was successfully refined from 22.1 to 4.5 μm after multi-pass warm rolling with falling temperature and annealing. Compared to the as-received sheet, the multi-pass warm rolled sheets in annealed condition exhibited weaker (0001) basal texture intensity, which resulted in the significantly increased Schmid factor of 〈a〉 basal slip. After multi-pass warm rolling with falling temperature, the rolled sheets in annealed condition also exhibited much better mechanical properties, e.g., higher tensile strength, larger fracture elongation, and higher Erichsen value, especially the IE of 8-pass warm rolled sheet in annealed condition was significantly increased by ∼33% under the same thickness, which could be attributed to the refined grain microstructure and the weakened basal texture.

We suggest a new method to evaluate stress directionality, the ratio of principal stresses, using nanoindentation by introducing a modified Berkovich indenter that is extended in one direction from the Berkovich indenter. In a nonequibiaxial stress state, the indentation load-depth curves are shifted differently as the extended axis of the indenter is placed in accordance with each principal direction. The indentation load-difference is proportional to each principal stress and the slopes are defined by the normal and parallel conversion factors whose ratio is constant at 0.58. The suggested method was verified by indentation tests using five nonequibiaxial stressed specimens. The evaluated stress directionality results show agreement with the applied reference values within ±20%. Furthermore, we calculated the conversion factor ratios for other modified Berkovich indenters extended to different degrees through finite element analysis and confirmed that the conversion factor ratio was inversely proportional to the extension of the modified Berkovich indenter.

The catalytic property toward oxygen reduction reaction (ORR) plays a significant role in the power generation of fuel cells (FCs). Here we demonstrate a graphene/activated carbon aerogel (GA/AC) composite to facilitate the ORR process, which is synthesized by a one-step hydrothermal method. The aligned pores and high porosity enable its mass density 20-times lighter than bare AC. Electrochemical studies show that the composite exhibits a remarkably improved electro-catalytic performance. The onset potential shifts positively from 0.68 to 0.83 V, and the number of electrons transferred is increased from 2.85 to 3.52, indicating that a four-electron pathway dominates the ORR process. This composite presents a mesoporous structure containing a large number of multi-scale pores and having a high specific surface area of 758.19 m2/g, which is responsible for its excellent onset potential and charge transfer rate. These aerogel-composites show great potential as ORR catalysts for assembling lightweight FCs and metal-air batteries.

Previously known to form only under high pressure synthetic conditions, here we report that the T′-type 214-structure cuprate based on the rare earth atom Tb is stabilized for ambient pressure synthesis through partial substitution of Pd for Cu. The new material is obtained in purest form for mixtures of nominal composition Tb1.96Cu0.8Pd0.2O4. The refined formula, in orthorhombic space group Pbca, with a = 5.5117(1) Å, b = 5.5088(1) Å, and c = 11.8818(1) Å, is Tb2Cu0.83Pd0.17O4. An incommensurate structural modulation is seen along the a axis by electron diffraction and high resolution imaging. Magnetic susceptibility measurements reveal long-range antiferromagnetic ordering at 7.9 K, with a less pronounced feature at 95 K; a magnetic moment reorientation transition is observed to onset at a field of approximately 1.1 T at 3 K. The material is an n-type semiconductor.

In this study, the bioactivity and cytocompatibility of electrospun polyamide 6 (PA6)/hydroxyapatite (HA) coating on zirconia-toughened alumina (ZTA) were investigated. Adjusting the PA6/HA ratio to 1.15 (w/w) had a significant role in achieving an appropriate fibrous coating with an average diameter of 120 ± 10 nm and surface porosity of 64.3%. The surface of bare and coated samples was hydrophilic, which promoted bone regeneration. The adhesion test of the PA6/HA mat demonstrated that a cohesive coating was formed on the ZTA via electrospinning. The in vitro bioactivity test of the PA6/HA coating in simulated body fluid (SBF) corroborated the formation of a nanostructured bonelike apatite phase. Cytocompatibility of the samples was evaluated through in vitro osteosarcoma-like cell (MG63) culture assays. The cytotoxicity study showed that the electrospun PA6/HA coating significantly improved cell attachment and spreading. The development of such bioactive, biomedical coatings opens new avenues for bone tissue engineering applications.

Aluminum gallium nitride (AlGaN) metal–semiconductor–metal photodetectors were successfully fabricated with different contact materials and structures and were tested with ultrafast lasers. The experimental results were compared with the finite element simulations based on APSYS and showed consistent trend with respect to the device I–V properties and response behaviors. Persistent photoconductivity (PPC) was observed for devices with both gold and aluminum contacts and various structures, and the decay time can be longer than 10 ms. The response time and responsivity were found to be affected by the bias voltage, operating temperature, and incident power. The mechanism behind the long decay time is analyzed from the perspective of the materials properties and factors influencing the decay time are examined. The nature of the metal–semiconductor contact is studied to help understand the PPC effect, and the contact showed ohmic-like behavior.

In this paper, Sm3+-doped silicate glasses containing AgNO3 were obtained by the common melting quenching method. Influence of AgNO3 concentration on the absorption and emission characteristics of Sm3+ were systematically investigated. With the increase of AgNO3 content from 0 to 3.0 wt%, the ultraviolet region absorption edge shows a slight blue-shift from 275 to 260 nm. Exciting by 255 nm, the visible emission intensity of Sm3+-doped silicate glass containing 0.5 wt% AgNO3 was about 31 times stronger than that of Sm3+ singly doped silicate glass. Fluorescence decay curves for the visible emission followed double exponential decay. Two fluorescence lifetimes were obtained, one was about 7–20 μs which was comparable with the lifetimes of 350 nm emission which derived from Ag+, another was about 2 ms which was comparable with that of the visible emission from Sm3+ excited by 401 nm. Thus, the significant enhancement visible emission of Sm3+ excited by 255 nm can be ascribed to the energy transfer from Ag+ to Sm3+.

While most papers on high-entropy alloys (HEAs) focus on the microstructure and mechanical properties for structural materials applications, there has been growing interest in developing high-entropy functional materials. The objective of this paper is to provide a brief, timely review on select functional properties of HEAs, including soft magnetic, magnetocaloric, physical, thermoelectric, superconducting, and hydrogen storage. Comparisons of functional properties between HEAs and conventional low- and medium-entropy materials are provided, and examples are illustrated using computational modeling and tuning the composition of existing functional materials through substitutional or interstitial mixing. Extending the concept of high configurational entropy to a wide range of materials such as intermetallics, ceramics, and semiconductors through the isostructural design approach is discussed. Perspectives are offered in designing future high-performance functional materials utilizing the high-entropy concepts and high-throughput predictive computational modeling.

In this study, a facile room-temperature solution method is developed for the preparation of zinc oxide@graphene oxide (ZnO@GO) nanocomposites. Unlike the general process to obtain crystallized materials by heating, the room temperature we used can generate fine ZnO@GO nanocomposites with ultra-small ZnO nanocrystal (∼8 nm) and high weight content (∼84%). The obtained ZnO@GO nanocomposite was thoroughly characterized by various physicochemical techniques such as scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy, indicating well-dispersed ZnO on the GO layer and strong interaction between the each other. As an anode material for lithium-ion batteries, ZnO@GO exhibits high specific reversible capacity and excellent cycling performance, which can be ascribed to the role of GO in preventing the agglomeration of the ZnO nanoparticles by creating the decorated nanoscale composite during the electrochemical process.

Hydrogen exposure has been found to result in metal embrittlement. In this work, we use nanoindentation to study the mechanical properties of polycrystalline tungsten subjected to deuterium plasma exposure. For the purpose of comparison, nanoindentation tests on exposed and unexposed reference tungsten were carried out. The results exhibit a decrease in the pop-in load and an increase in hardness on the exposed tungsten sample after deuterium exposure. No significant influence of grain orientation on the pop-in load was observed. After a desorption time of td ≥ 168 h, both the pop-in load and hardness exhibit a recovering trend toward the reference state without deuterium exposure. The decrease of pop-in load is explained using the defactant theory, which suggests that the presence of deuterium facilitates the dislocation nucleation. The increase of hardness is discussed based on two possible mechanisms of the defactant theory and hydrogen pinning of dislocations.