Different parts of a casting may receive different microstructures during cooling particularly for the large scale casting, which can affect the fatigue behavior. In the present study, in consideration of the safety and reliability, the microstructures, tensile properties, and high cycle fatigue behaviors of different regions in a low-pressure sand-cast Mg–10Gd–3Y–0.5Zr (GW103K) magnesium alloy component with large scale and complicated structure were investigated. The results showed that the tensile properties particularly ultimate tensile strength (UTS) and elongation (EL) varied with regions and the fatigue strength varied in a range from 100 to 115 MPa. In addition, crack initiation, crack propagation, and fracture behavior of the studied alloys after tensile test and high cycle fatigue test were also investigated systematically.

Carbon foams were successfully fabricated from sucrose and kaolinite clay by thermo-foaming method using aluminum nitrate as the blowing agent. The phases, pore structure, and compressive strength were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and mechanical test, respectively. The foams had porous structure with spherical open cells of size in the range of 400–1000 μm, dense struts, and interconnected voids of size in the range of 100–600 μm. Both smooth and coarse types of voids are observed. Mullite and cristobalite, products of the clay mineral, are concentrated more on the strut and cell walls. The ultimate compressive strength evolution is found to be in correlation with the amount of voids and the microcracking in the carbon foams.

Additive manufacturing (AM) holds tremendous promise in terms of revolutionizing manufacturing. However, fundamental hurdles limit the widespread adoption of this technology. First, production rates are extremely low. Second, the physical size of the parts is generally small, less than a cubic foot. Third, the mechanical properties of the polymer parts are generally poor, limiting the potential for direct part replacement and functional use of the polymer components. This article describes various ways in which carbon fibers (CFs) can be used to address these fundamental hurdles. First, CF-reinforced polymers developed for AM have demonstrated specific strengths approaching aerospace-quality aluminum. Second, CF additions can radically reduce the distortion and warping of the material during deposition, which enables large-scale, out-of-the-oven, high deposition rate manufacturing. Finally, the complementary nature of CF technology and AM is discussed, showing how merging the two manufacturing processes enables the construction of complex components that would not be possible with either technology alone.

Al6061 and AZ31 plates were processed using accumulative roll bonding (ARB) method up to two passes to produce laminated composites. The sandwich stacks of Al6061/AZ31/Al6061 were held at 450 °C for 10 min in a cubical furnace and rolled together with reduction of 50% in one pass. The microstructural investigations were done using optical and scanning electron microscopes. The structures of the interface, mechanical and drop impact properties of the laminated composites after the first and second passes were investigated and compared with Al6061 and AZ31 alloy plates. It was found that Al6061 improved the elongation to failure property of AZ31 after the first pass of ARB process and the drop impact properties of AZ31 after the first and second passes. However, elongation to failure magnitude with the uniaxial tensile loading decreased with increase in the number of passes due to the formation of brittle intermetallic between the Al6061/AZ31 nonuniform interfaces.

We present a simple and quick procedure for the one-pot synthesis of manganese oxides under a basic solvothermal condition in the presence of cationic surfactants acting as the template in a 2-butanol/water solution. Three-dimensional spinel-type MnO2 microspheres composed of small nanoparticles have been fabricated for the first time using our method. Their corresponding electrochemical performances in the applications of supercapacitor electrodes exhibit a good specific capacitance (SC) value of ∼190 F/g at 0.5 A/g and excellent SC retention and Coulombic efficiency of ∼100% and ∼95% after 1000 charge/discharge cycles at 1 A/g, respectively. This suggests its potential applications in energy storage devices. Further, we demonstrate that this solvothermal technique enables the morphological tuning of manganese oxides in various forms such as schists, rods, fibers, and nanoparticles. This work describes a rapid and low-cost technique to fabricate novel architectures of manganese oxides having the desired crystal phase, which will highly benefit various supercapacitor applications.

A facile inexpensive route has been developed to prepare ZnO hierarchical materials with microplate/nanohole structures based on the colloidal monolayer template by the precursor thermal decomposition. These hierarchical structured materials demonstrated an excellent superhydrophobicity with self-cleaning effect and an enhanced photocatalytic performance to organic molecules, which are attributed to big roughness and large surface area of such special hierarchical structures. The formation mechanism of such hierarchical structures was investigated in detail by tracing morphology changing at different precursor concentrations. At high precursor concentration, both incompletely restricted ZnO growth of colloidal templates and preferable growth of microplates take place at the same time, and hence, ZnO hierarchical materials with microplate/nanohole structures are formed. With increasing precursor concentration, the number density of ZnO microplates tends to be larger. The large number density of ZnO microplates and holes on the microplates render the sample a large surface area and surface roughness, leading to good superhydrophobicity and photocatalytic activity. Such hierarchical ZnO micro/nanostructured materials have important applications in environmental science, microfluidic devices, etc.

In this paper, a modeling method was introduced for SiC particle reinforced aluminum matrix composite. Micro-indentation technique was used to study the micro properties of both SiC particles and aluminum matrix with Micro-Compression-Tester. Mechanical properties like Young's modulus and hardness were calculated using Oliver and Pharr method. After repeated experiments, the average Young's modulus and the hardness of matrix and particle were calculated as 76.8 and 334.7 GPa, 1.58 and 32.56 GPa, respectively. During the indentation experiments on particle, the phenomenon of particle acting as “second indenter” was detected from the recorded P–h curves. Besides, the material elastic–plastic properties of matrix were analyzed using inverse method. Based on the micro material properties from indentation, the indentation processing of particle as second indenter has been simulated. Also, the simulation model at micro scale has been established by using such material properties for further investigation.

Ta2O5 added MgCuZn ferrites are prepared by the microwave-hydrothermal (M-H) processing. The nanocrystalline ferrites are sintered to a temperature of 900 °C using conventional sintering (CS) and microwave sintering (MW) methods. The effect of Ta2O5 addition on the microstructure, d.c. resistivity, and Curie temperature of the ferrites has been studied. By the addition of Ta2O5 to MgCuZn ferrites, resistivity decreases without grain growth. The complex permittivity and complex permeability of the prepared samples were measured in the frequency range from 10 kHz to 1.8 GHz. The value of ε′ and tan δ for all the samples decreases from 10 to 100 kHz and almost remains constant up to 300 MHz and increases further by increasing the frequency up to 1 GHz. The µ* spectra are analyzed into two magnetization processes with a focus on the grain size of the ferrite samples. The present ferrites exhibited high values of permeability (>1000) in the frequency range of 10 kHz to 50 MHz. Then the values of permeability are found to decrease with an increase in frequency up to 180 MHz and finally, frequency dispersion occurred at 200 MHz.

We report the effect of nonstoichiometry on the terahertz absorption of fully dense optical ceramics of Y3Al5O12 and compare to that of undoped and 1 at.% Nd3+ doped single crystals. Our research is motivated primarily by the necessity of having better control of stoichiometry during the preparation of transparent yttrium aluminum garnet (YAG) ceramics. A set of twenty ceramic samples was prepared by solid-state sintering of Y2O3 and Al2O3 powder mixtures with compositions ranging from −0.62 to +0.96 mol% of Y2O3 on each side of the stoichiometric garnet composition. After sintering, the samples were highly translucent in the visible range, with attenuations better than 2 cm−1. These samples were characterized using time-domain terahertz spectroscopy between 0.06 and 2.8 THz. Ceramic and single-crystal samples exhibit a similar broad absorption band, which we assign to a 2-phonon difference process, and whose width and intensity depend upon composition.

The effect of electric-current pulses on the evolution of microstructure and texture in cryogenically rolled copper was determined. The pulsed material was found to be completely recrystallized, and the recrystallization mechanism was deduced to be similar to that operating during conventional static annealing. The microstructural changes were explained simply in terms of Joule heating. A significant portion of the recrystallization process was concluded to have occurred after pulsing; i.e., during cooling to ambient temperature. The grain structure and microhardness were shown to vary noticeably in the heat-affected zone (HAZ); these observations mirrored variations of temper colors. Accordingly, the revealed microstructure heterogeneity was attributed to the inhomogeneous temperature distribution developed during pulsing. In the central part of the HAZ, the mean grain size increased with current density and this effect was associated with the temperature rise per se. This grain size was slightly smaller than that in statically recrystallized specimens.

Epitaxial graphene of uniform thickness prepared on SiC is of great interest for various applications. On the Si-face, large area uniformity has been achieved, and there is a general consensus about the graphene properties. A similar uniformity has yet not been demonstrated on the C-face where the graphene has been claimed to be fundamentally different. A rotational disorder between adjacent graphene layers has been reported and suggested to explain why multilayer C-face graphene show the π-band characteristic of monolayer graphene. Utilizing low energy electron microscopy, x-ray photoelectron electron microscopy, low energy electron diffraction, and photoelectron spectroscopy, we investigated the properties of C-face graphene prepared by sublimation growth. We observe the formation of micrometer-sized crystallographic grains of multilayer graphene and no rotational disorder between adjacent layers within a grain. Adjacent grains are in general found to have different azimuthal orientations. Effects on C-face graphene by hydrogen treatment and Na exposure were also investigated and are reported. Why multilayer C-face graphene exhibits single layer electronic properties is still a puzzle, however.