Electroplastic manufacturing processing (EPMP) is a relatively new metal-forming process that is energy efficient, environmentally friendly, and versatile. In particular, it can be used to manufacture metals or alloys that are difficult to process by conventional manufacturing protocols. There have been significant advances in EPMP in the past decade, and this review summarizes our current state of understanding and describes recent developments in EPMP. Particular emphasis is placed on describing the mechanisms responsible for the electroplastic effect and microstructure evolution as well as major advances in EPMP of metals. Challenges facing theoretical and experimental investigations are also discussed.

The influence of temperature on the indentation size effect is explored experimentally. Copper is indented on a custom-built high-temperature nanoindenter at temperatures between ambient and 200 °C, in an inert atmosphere that precludes oxidation. Over this range of temperatures, the size effect is reduced considerably, suggesting that thermal activation plays a major role in determining the length scale for plasticity.

The dynamic uniaxial compressive behavior of Zr-based metallic glasses under a wide high strain rate was studied by a miniaturized split Hopkinson pressure bar, including high strain rate up to 104 s−1. Experimental results indicate that the uniaxial compressive failure stress would decrease suddenly and then tend to hold steady with increasing strain rate. This phenomenon provides a generalized perspective for understanding the effect of local heat generation on the deformation of metallic glasses under dynamic loads.

A new low sintering temperature microwave dielectric ceramic, Li2ZnTi3O8, was investigated. X-ray diffraction data show that Li2ZnTi3O8 has a cubic structure [P4332(212)] with lattice parameters a = 8.37506 Å, V = 587.44 Å3, and Z = 4 when the sintering temperature is 1050 °C. The Li2ZnTi3O8 ceramic exhibits good microwave dielectric properties with εr about 26.2, Q×f value about 62,000 GHz, and τf about −15 ppm/°C. The addition of BaCu(B2O5) can effectively lower the sintering temperature from 1050 to 900 °C without degrading the microwave dielectric properties. Compatibility with Ag electrode indicates this material can be applied to low temperature cofired ceramic devices.

Two novel La3+ and Ti4+ cosubstituted Sr3LaNb3O12 ceramics, Sr2La2TiNb2O12 and SrLa3Ti2NbO12, were prepared and the effect of substitution on the microwave dielectric properties was investigated. Results showed that as the amounts of substitution increased, dielectric constant (εr) increased from 36 to 41, and temperature coefficient of resonant frequency (τf) improved from −9 to 3 ppm/°C, whereas the quality factor (Q×f) decreased from 45,000 to 33,600 GHz. A temperature-stable microwave dielectric ceramics SrLa3Ti2NbO12 with τf of 3 ppm/°C, εr of 41, Q×f of 33,600 GHz was obtained; it might be a promising candidate for practical application in base stations if the quality factor is enhanced beyond 40,000 GHz.

Y2Ba4CuNbO12 (Y-24Nb1) and silver (Ag) are recognized as potential candidates for improving both flux pinning and the mechanical properties of bulk rare earth (RE)–Ba–Cu–O [(RE)BCO] high-temperature superconductors (HTS). Recent attempts to add Ag2O to superconducting Y-123/Y2Ba4CuNbO12 composites, however, have produced a highly anisotropic morphology of Ag particles in samples grown by top-seeded melt growth (TSMG). This morphology has been attributed to strong particle pushing effects due to the presence of Y-24Nb1 nanoparticles in the composite microstructure. An investigation of the formation of anisotropic Ag particles in the YBCO bulk microstructure indicates that these pushing effects generate different morphological microstructural zones in the composite. These include a zone free of inclusions other than acicular Ag particles, a zone of segregated additives (i.e., Y-24Nb1, Y-211, and Ag), and a zone containing fine Ag and other particles distributed uniformly throughout the local microstructure. The particle pushing/trapping theory has been used to explain these extraordinary features of the distribution of Ag inclusions. The superconducting and mechanical properties of samples containing very fine silver inclusions are also discussed briefly.

A new elpasolite-type (NH4,K)3VO2F4 compound was prepared and characterized by x-ray diffraction, differential scanning calorimeter (DSC), impedance analysis, and electrical polarization measurements. It crystallizes in an orthorhombic lattice with unit-cell parameters: a = 8.9584(4), b = 18.6910(14), c = 6.2174(4) Å, V = 1041.04(11) Å3, Z = 6. NH4+, and K+ ions are distributed statistically over crystallographically four equivalent sites. There are two distinguishable vanadium atoms forming cis- and trans-VO2F4 octahedra present in the unit cell. High-temperature studies by DSC and in situ x-ray diffraction revealed a first-order structural transformation from orthorhombic to cubic lattice around 343 K. Impedance measurements show two different kinds of conductivity behaviors for the two phases. In orthorhombic phase a significant conductivity resulting from involvement of protonic species is observed. In the orthorhombic phase, a clear ferroelectric hysteresis loop is observed.

We report a novel method of growing silver nanostructures by cathodic sputtering onto an ionic liquid (IL) and our visualization by transmission cryo-electron microscopy to avoid beam-induced motion of the nanoparticles. By freezing the IL suspension and controlling electron dose, we can assess properties of particle size, morphology, crystallinity, and aggregation in situ and at high detail. We observed round silver nanoparticles with a well-defined diameter of 7.0 ± 1.5 nm that are faceted with crystalline cubic structures and ˜80% of the particles have multiply twinned faults. We also applied cryo-electron tomography to investigate the structure of the nanoparticles and to directly visualize the IL wetting around them. In addition to particles, we observed nanorods that appear to have assembled from individual nanoparticles. Reexamination of the samples after 4–5 days from initial preparation showed significant changes in morphology, and potential mechanisms for this are discussed.

Type II ZnO/ZnSe core/shell nanowire arrays were grown by a two-step chemical vapor deposition. The nanowire arrays with dense nanoislands on the surface are well aligned and normal to the substrate imaged by scanning electron microscopy. The core/shell structure of nanowires was identified by a high-resolution transmission electron microscopy. The structure and composition of the shell were confirmed to be wurtzite ZnSe by x-ray diffraction, Raman scattering and energy-dispersive x-ray spectroscopy. Moreover, an intense emission was observed at 1.89 eV smaller than the band gaps of core and shell materials by photoluminescence, indicating the achievement of the type II band alignment at the interface. This study is expected to contribute to the potential applications in novel photovoltaic devices.

Highly dispersed ZnO/TiO2 nanotube composites (NTCs) were successfully synthesized by a facile ethylenediamine-assisted deposition-precipitation route. The characterizations from x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller, Fourier transform infrared, and ultraviolet-visible spectra revealed that hexagonal wurtzite phase ZnO NPs with an average size of about 2 nm were homogeneously dispersed and anchored on the surface of TiO2 nanotubes (NTs) to form ZnO/TiO2 NTCs. The as-prepared ZnO/TiO2 NTCs with the atom ratio Zn/Ti of 1:4 exhibited excellent photocatalytic activity for photodegradation of methyl orange compared with P25 and pure TiO2 NTs, which were mainly caused by an increase of interfacial charge transfer reactions and a decrease of electron-hole pair recombination on ZnO-TNTs heterojunction. Furthermore, ZnO/TiO2 NTCs possessed favorable recycle efficiency due to their relatively high sedimentation rate and only a slight decrease of photocatalytic activity after a six time recycle.

Modified embedded-atom method (MEAM) interatomic potentials for Nb-C, Nb-N, Fe-Nb-C, and Fe-Nb-N systems have been developed based on the previously developed MEAM potentials for lower order systems. The potentials reproduce various fundamental physical properties (structural properties, elastic properties, thermal properties, and surface properties) of NbC and NbN, and interfacial energy between bcc Fe and NbC or NbN, in generally good agreement with higher-level calculations or experimental information. The applicability of the present potentials to atomic-level investigations to the precipitation behavior of complex-carbonitrides (Nb,Ti)(C,N) as well as NbC and NbN, and their effects on the mechanical properties of steels are also discussed.

In-depth studies of the two types of Te nanoprecipitates, linear and elliptic, in Cd1–xZnxTe (CZT) crystals grown by a modified vertical Bridgman method have been carried out. Electron diffraction suggests that linear Te nanoprecipitates align their Te atoms in a similar way to CZT structure, while elliptic Te nanoprecipitates cluster Te atoms following the pure trigonal Te structure. The three-dimensional morphology for both linear and elliptic Te nanoprecipitates has been revealed by delicate energy-dispersive x-ray analysis under electron microscopy. The density of elliptic Te nanoprecipitates ranges from 1015 to 1017 cm−3, while linear ones usually several times lower for a certain CZT wafer. The origin of both types of Te nanoprecipitates has been discussed in terms of the local density of intrinsic point defects in CZT. CZT properties are influenced more negatively by elliptic Te nanoprecipitates, which shed light on the methodology for crystal growth: preventing the clustering of intrinsic point defects during the crystal growth will be essential to obtain high quality CZT crystal.

Electroless nickel (Ni–P) is a common surface finish used in the ball grid array (BGA) package and interfacial reactions between its surface finish and lead-free solders can form complex intermetallic compound (IMC) layers. The presence of minor elements in lead-free solders either intentionally added or due to impurity contamination during solder manufacturing, can affect the solder-joint performance. In this work, interfacial reactions between Ni–P surface finish and the Sn–Ag–Cu solders were modified by varying Ag and Cu contents and also by adding a small amount of minor elements such as phosphorus (P), indium (In), and germanium (Ge). A transmission electron microscope was used to determine the intermetallic layer phases, compositions, crystal structures, and void defects. Varying the solder alloy elements led to the modulation of voids formation.

The microstructure and microimpact performance of Sn1Ag0.1Cu0.02Ni0.05In (SAC101NiIn)/AuNi/Cu solder ball joints were investigated after a thermal cycle test (TCT). The joints show complete bulk fracture behavior before TCT. Moreover, TCT facilitated interfacial fracture behavior with lower fracture energy. The intermetallic compounds (IMCs) formed in the solder joints before and after TCT were investigated. TCT induces a variety of structural variations in the solder joints, including slipping bands, whisker formation, the squeezing of the IMC layer, the formation of cavities, the rotation and pop-up of grain, and the deformation and rotation of the entire joint. The variations in fracture behavior induced by TCT are correlated with the structural variations in the solder joints.

Sn-xCu/Ni-yCo (x = 0.2–1.0 wt%, y = 10, 20, 40 at.%) interfacial reactions at 250 °C are examined in this study. Sn-Cu alloys are promising lead free solders, and Ni-Co alloys are the potential diffusion barrier layer materials in flip chip packaging. The Co and Cu effects on the Sn-Cu/Ni-Co interfacial reactions are examined. When the Co addition is 10 at.%, the reaction phases are the Ni3Sn4 and Cu6Sn5 phase, and Sn-Cu/Ni-10at.%Co interfacial reactions are similar to those of Sn-Cu/Ni. When the Co addition is 20 at.%, the CoSn2 phase is formed, and the reaction path is Sn-Cu/Ni3Sn4/CoSn2/Ni-20at.%Co. When the Co addition is 40 at.%, only Sn-Co binary phases are formed (CoSn2 and CoSn3), and Sn-Ni binary phases are not formed. The Cu6Sn5 phase is not formed until the Cu content is higher than 0.7 wt%. The Cu concentration effect is the main drawback of using Ni as the diffusion barrier layer material and the Sn-Cu solders. The Cu concentration effect of the Sn-Cu/Ni-Co interfacial reactions is not as pronounced as that of Sn-Cu/Ni.

Carbon nanofiber-supported Pt–Pd alloy composites were prepared by co-electrodepositing Pt–Pd alloy nanoparticles directly onto electrospun carbon nanofibers. The morphology and size of Pt–Pd alloy nanoparticles were controlled by the surface treatment of carbon nanofibers and the electrodeposition duration time. Scanning electron microscopy/energy dispersive spectrometer (SEM)/(EDS) and x-ray photoelectron spectroscopy (XPS) were used to study the composition of Pt–Pd alloy on the composites, and the co-electrodeposition mechanism of Pt–Pd alloy was investigated. The resultant Pt–Pd/carbon nanofiber composites were characterized by running cyclic voltammograms in oxygen-saturated 0.1 M HClO4 at 25 °C to study their electrocatalytic ability to reduce oxygen. Results show that Pt–Pd/carbon nanofiber composites possess good performance in the electrocatalytic reduction of oxygen. Among all Pt–Pd/carbon nanofibers prepared, the nanofiber composite with a Pt–Pd loading of 0.90 mg/cm2 has the highest electrocatalytic activity by catalyst mass.

Particle-containing silica sol was synthesized by co-hydrolysis and co-condensation of two silane precursors, tetraethylorthosilicate (TEOS) and an organic silane composed of a non-hydrolyzable functional group (e.g., alkyl, fluorinated alkyl, and phenyl), and used to produce superhydrophobic coatings on fabrics. It has been revealed that the non-hydrolyzable functional groups in the organic silanes have a considerable influence on the fabric surface wettability. When the functional group was long chain alkyl (C16), phenyl, or fluorinated alkyl (C8), the treated surfaces were highly superhydrophobic with a water contact angle (CA) greater than 170°, and the CA value was little affected by the fabric type. The washing durability of the superhydrophobic coating was improved by introducing the third silane containing epoxide group, 3-glycidoxypropyltrimethoxysilane (GPTMS), for synthesis. Although the presence of epoxide groups in the coating slightly reduced the fabrics' superhydrophobicity, the washing durability was considerably improved when polyester and cotton fabrics were used as substrates.

The dynamics of track development due to the passage of relativistic heavy ions through solids is a long-standing issue relevant to nuclear materials, age dating of minerals, space exploration, and nanoscale fabrication of novel devices. We have integrated experimental and simulation approaches to investigate nanoscale phase transitions under the extreme conditions created within single tracks of relativistic ions in Gd2O3(TiO2)x and Gd2Zr2–xTixO7. Track size and internal structure depend on energy density deposition, irradiation temperature, and material composition. Based on the inelastic thermal spike model, molecular dynamics simulations follow the time evolution of individual tracks and reveal the phase transition pathways to the concentric track structures observed experimentally. Individual ion tracks have nanoscale core-shell structures that provide a unique record of the phase transition pathways under extreme conditions.

Wurtzite ZnO nanorods were grown from solution onto coarse-grain bulk polycrystalline Ag substrates to explore the nature of preferred heteroepitaxial orientations. ZnO nanorods grow copiously on grains with <111> and <001> surface normals. Two epitaxial orientations were observed: {0001} ZnO ‖ {111} Ag with <20> ZnO ‖ <10> Ag and {0001} ZnO ‖ {001} Ag with <20> ZnO ‖ <10> Ag. Both feature ZnO basal plane growth, and the specific in-plane orientation relationships both feature alignment of close-packed directions in the interface. Nanorod growth was strongly suppressed on Ag grains in most other orientations. Although strain energy minimization is often invoked to explain the {0001} ZnO ‖ {111} Ag with <20> ZnO ‖ <10> Ag orientation, associated with an almost ideal near-coincidence site lattice matching, our data suggests that strain may not be the sole, or even the most important, determinant of the preferred orientations during solution-based epitaxial growth in this system.

The initiation and detonation properties of explosives are often empirically correlated to density, surface area, and particle size. Although these correlations are sometimes used successfully to predict the performance of bulk samples, the data are spatially averaged, which unfortunately muddles information critical to understanding fundamental processes. Density and surface area are essentially an indirect measure of porosity, which is arguably a more appropriate metric in many applications. We report the direct characterization of porosity in polycrystalline molecular crystal explosives by focused ion beam nanotomography, a technique that is typically reserved for robust materials such as ceramics and metals. The resulting three-dimensional microstructural data are incredibly rich, promising a substantial advance in our ability to unravel the processes governing initiation and detonation of molecular crystal explosives. In a larger context, this work demonstrates that focused ion beam nanotomography may be successfully extended to the investigation of nanoscale porosity in other molecular crystal or polymer materials.