The objective of this study was to identify the microstructural mechanisms controlling Ω precipitates’ contribution to the high strength and ductility of Al–Cu–Mg–Ag alloys subjected to high impact loading conditions. Three interrelated approaches were used: (i) HRTEM imaging of deformed Ω precipitates in ballistically impacted Al–Cu–Mg–Ag plates, (ii) microstructurally based finite element (FE) analysis based on specialized crystalline plasticity formulations, and (iii) molecular dynamics (MD) simulations of dislocation nucleation and emission. The FE and MD simulations detail the evolution of dislocation densities and dislocations at the Al/Ω interface, which are consistent with the experimentally observed multiplicity of shear cutting of thin Ω precipitates. Furthermore, the FE results indicate that unrelaxed tensile strains at the Al/Ω interface can inhibit localized deformation in the alloy.

A procedure for predicting the in-plane and out-of-plane thermal conductivities of woven fabric composites through a combined approach of the representative volume element method and heat transfer analyses via finite element is presented. The representative volume element method was implemented using two unit cells established at different length scales with periodic boundary conditions. The procedure was exemplified on a plain weave glass fabric reinforced epoxy resin matrix composite. Sensitivity studies were conducted to quantify the influence of fiber volume fraction and thermal conductivity of the constituent phases on the effective thermal conductivities of the composite. The procedure, which can be implemented into commercial finite element codes, is an efficient tool for the design of woven fabric composites.

Nanoparticles of Cd1–xCuxS (x = 0–0.15) were synthesized by chemical coprecipitation using thiophenol as a capping agent. The x-ray diffraction patterns reveal that the pure and doped CdS nanoparticles are single phase with cubic zinc blende structure. The transmission electron microscopy shows the average size of the nanoparticles is about 8.5 nm. Optical absorption spectra indicate the energy gap decreases with increasing Cu2+ concentration. The broad emission peak around 520 nm is completely quenched with increasing Cu2+ content. The electron spin resonance analysis also confirms the Cu (II) ion to be doped substitutionally in CdS nanoparticles and the Lande factor of all the samples with sharp resonance is g = 2.0.

Interfacial reaction and microstructure evolution in a Zr2Al3C4 reinforced Cu composite were studied by x-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Decomposition of Zr2Al3C4 was triggered by the deintercalation of Al atoms. In the initial reaction stage, depletion of Al occurred locally. ZrC and Cu platelets as well as thin twinned ZrC slices were observed inside the Zr2Al3C4 grains. In the later reaction stage, all Al atoms depleted from Zr2Al3C4 and were dissolute into the Cu matrix. The final reaction products were a Cu–Al solid solution, ZrC0.5, and highly disordered graphite, which resulted in large volume shrinkage. These experimental results provided a baseline for controlling interfacial reaction and microstructure development in Cu/Zr2Al3C4-based particle-reinforced Cu composites for optimized mechanical and electrical properties.

Strain evolution in 0.45-μm-thick, 2-μm-wide, and 100-μm-long Cu conductor lines with a passivation layer has been investigated using synchrotron x-ray microdiffraction. A moderate electromigration-current density of 2.2 × 105 A/cm2 was used to minimize Joule heating in the Cu conductor lines. After 120 h of current flowing in the Cu lines at 270 °C, measurements show strain relaxation and homogenization occurring in the Cu lines with current flowing, but not in Cu conductor lines without current. Stronger interaction between electrons with Cu atoms in areas with higher strains was proposed to explain the observation.

We reported a simple and convenient method to determine the film thickness by nanoindentation tests. This method starts from the analysis of the unloading portion of the measured nanoindentation load-displacement curves according to a quadratic polynomial, P = α(h − hf)2 − P0, where P is the indentation load, P0 is the virtual load used to consider the effect of the residual contact stress, h is the indenter displacement (penetration depth), hf is the final displacement after complete unloading which should be determined by curve fitting, and α is a constant. Then the best-fit value of the parameter P0 is plotted as a function of the maximum penetration depth, hmax. Such a P0 versus hmax curve may pass through a minimum, and hmax corresponding to this minimum would be equal to the film thickness value.

Transport properties in the a-b plane of Nd0.75Sr1.25CoO4 thin film as fabricated via a pulsed laser deposition technique have been investigated by means of measurements of resistivity and thermopower, respectively, in the temperature ranges of 76-300 and 80-310 K. The thermopower of the specimen revealed a mechanism of spin-dependent scattering of the charge carriers where its conduction could be well interpreted by the small polaron hopping conduction in the nonadiabatic regime at high temperatures and the two-dimensional variable range hopping of small polarons at low temperatures. Possible mechanisms for the polaronic conduction were also discussed in the article where several physical parameters of the specimen were determined using a small polaron hopping model and a better understanding of the strongly correlated electron system was achieved.

Evolution of deformation texture in commercially pure titanium with submicron grain size (SMG) was studied using x-ray diffraction (XRD) and electron back scatter diffraction (EBSD) methods. The material was deformed by rolling at room temperature. The deformation mechanism was found to be slip dominated with a pyramidal <c + a> slip system facilitating plastic deformation. No evidence of tensile or compressive twinning was detected, as generally seen in the case of titanium with conventional microcrystalline grain size. The absence of twinning and the propensity of the pyramidal <c + a> slip system in the SMG Ti is attributed to the lack of coordinated motion of zonal partial dislocations that leads to twinning.

Electromigration behavior and fast circuit failure with respect to crystallographic orientation of Sn grains were examined. The test vehicle was Cu/Sn–3.0 wt% Ag–0.5 wt% Cu/Cu ball joints, and the applied current density was 15 kA/cm2 at 160 °C. The experimental results indicate that most of the solder bumps show different microstructural changes with respect to the crystallographic orientation of Sn grains. Fast failure of the bump occurred due to the dissolution of the Cu circuit on the cathode side caused by the fast interstitial diffusion of Cu atoms along the c-axis of the Sn grains when the c-axis was parallel to the electron flow. Slight microstructural changes were observed when the c-axis was perpendicular to the electron flow. In addition, Cu6Sn5 intermetallic compound (IMC) was formed along the direction of the c-axis of the Sn grains instead of the direction of electron flow in all solder ball joints.

N-type Bi2Te3 alloys with different microstructural length scales were prepared by mechanical milling and spark plasma sintering (SPS). The electrical resistivity, thermal conductivity, Seebeck coefficient, carrier concentration, and Hall mobility along and perpendicular to the loading direction were determined and characterized. The SPS sintered bulk disks using nanostructured powder contain high nanoporosity and weak (00l) texture along the loading axis, in contrast to those obtained with coarse powder. The influence of nanoporosity and texture on the thermoelectric and transport properties in the n-type Bi2Te3 alloys is discussed in light of the microstructural characteristics at different length scales.

Enthalpies of high-temperature phase transitions and fusion in lanthanum oxide (La2O3) were directly measured for the first time. Three samples were prepared by laser melting, sealed in tungsten crucibles, and heated in a differential thermal analyzer calibrated by melting Al2O3. Transformation enthalpy of La2O3 from A to H phase is 23 ± 5 kJ/mol at 2046 ± 5 °C and from H to X phase is 17 ± 5 kJ/mol at 2114 ± 5 °C. Lanthanum oxide melts at 2301 ± 10 °C, with enthalpy of fusion of 78 ± 10 kJ/mol.

Nitrogen-doped multiwalled carbon nanotubes (N-doped MWNTs) were synthesized in a large quantity by the pyrolysis of pyridine at various temperatures in the range of 750–950 °C. The influence of temperature on the morphology, composition, thermal stability, and bonding nature of N-doped MWNTs was investigated. It is found that the yield of N-doped MWNTs increases linearly with the increase of the growth temperature. The maximum N content (4.6 at%) in MWNTs was obtained from a sample grown at 900 °C. N-doped MWNTs synthesized at 950 °C possess a unique drumlike morphology with the highest oxidizing temperature (535 °C). It is evidenced that N atoms are incorporated into the graphitic network in three different bonding forms and their relative content is affected by the growth temperature, which shows a clear influence on the morphology of N-doped MWNTs.