The influence of shot peening (SP) on high cycle fatigue (HCF) performance of smooth and notched specimens of hot-extruded ZK60 magnesium alloy was investigated and compared to that of hot-extruded and T5 aging-treated ZK60 magnesium alloy referred to as ZK60-T5. The increases in fatigue properties at the optimum Almen intensities were found to depend on the material states. In contrast to ZK60 alloy, higher smooth and notched fatigue properties for both unpeened and peened specimens were observed for ZK60-T5 alloy. Meanwhile, the improvement of fatigue life for notched specimen by SP was much more than that for the smooth specimen. The mechanism by which the compressive residual stress induced by SP resulted in the improvement of fatigue performance of smooth and notched specimens for ZK60 and ZK60-T5 alloys was discussed.

The compositional dependence of glass formation and thermal and elastic properties was clarified for the ternary La–Al–Co bulk glass-forming system. The existing linear correlation between La concentration and characteristic temperatures, i.e., the glass transition temperature Tg and the onset temperature of crystallization Tx, as well as the elastic moduli in this system can give a useful guideline for the chemical design of desirable bulk metallic glasses (BMGs) with tunable physical properties in advance. The relationship between Tg and elastic constants for the La–Al–Co BMGs can be quantitatively described using a microscopic model proposed by T. Egami.

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.

Surfaces and buried interfaces play critical roles in many environmental, catalytic, and tribological processes and in a wide variety of applications, including microelectronics and optoelectronics. Interfacial structure and composition are closely coupled to their surroundings, and probes that yield information about materials in situ are essential to obtain a thorough understanding of interface functions and properties. The highly brilliant, hard x-rays available from synchrotron light sources can easily penetrate through gas or liquid environments, or even solid thin-film overlayers, and enable real-time monitoring of the evolving chemistry and structure of the interface with atomic-scale resolution. Here we review the in situ study of interfaces by a variety of synchrotron x-ray scattering techniques and provide several examples of their application in electrochemical processes and thin-film island growth. We also discuss recent advances in analytical techniques and x-ray optics that are facilitating the in situ study of surfaces and buried interfaces with direct imaging.

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.

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.

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.

Recent advances in x-ray and neutron sources, optics, and scattering methods are heralding a new age in the study of the structure and properties of complex materials. By providing unprecedented resolution in real space, reciprocal space, and time, new techniques address materials characterization challenges beyond anything possible before, at length scales ranging from the atomic scale to the mesoscale, and at times as short as femtoseconds. The high degree of coherence of third-generation synchrotron sources permits a new level of precision in the quantitative description and analysis of diffraction and scattering and allows beams with sizes probing individual nanostructures to be produced. As a result, in situx-ray and neutron analysis techniques now provide insight into the structure of nanomaterials and yield a more precise set of metrics describing the nanometer-scale structure of materials. Time resolution and in situ studies allow application of these techniques to materials driven far from equilibrium and to the challenging environment associated with materials processing.

Advances in nanoscale directed assembly strategies have enabled researchers to analogize atomic assembly via chemical reactions and nanoparticle assembly, creating a new nanoscale “periodic table.” We are just beginning to realize the nanoparticle equivalents of molecules and extended materials and are currently developing the ground rules for creating programmable nanometer-scale coordination environments. The ability to create a diverse set of nanoscale architectures from one class of nanoparticle building blocks would allow for the synthesis of designer materials, wherein the physical properties of a material could be predicted and controlled a priori. Our group has taken the first steps toward this goal and developed a means of creating tailorable assembly environments using DNA-nanoparticle conjugates. These nanobioconjugates combine the discrete plasmon resonances of gold nanoparticles with the synthetically controllable and highly selective recognition properties of DNA. Herein, we elucidate the beneficial properties of these materials in diagnostic, therapeutic, and detection capabilities and project their potential use as nanoscale assembly agents to realize complex three-dimensional nanostructures.

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.