In this work, glass formation under high-energy ball milling was investigated for a (Ti0.33Zr0.33Hf0.33)50(Ni0.33Cu0.33Ag0.33)40Al10 high-order alloy system with equiatomic substitution for early and late transition-metal contents. For comparison, an amorphous alloy ribbon with the same composition was prepared using the melt-spinning method as well. Structural features of the samples were characterized using x-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. Mechanical alloying resulted in a glassy alloy similar to that obtained by melt spinning. However, the glass formation was incomplete, and a small amount of unreacted crystallites smaller than 30 nm in size still remained in the final ball-milled product. Like the melt-spun glass, the ball-milled glassy alloy also exhibited a distinct glass transition and a wide supercooled liquid region of about 80 K. Crystallization of this high-order glassy alloy proceeded through two main stages. After the primary nanocrystallization was completed, the remaining amorphous phase also behaved as a glass, showing a detectable glass transition and a large supercooled liquid region of about 100 K.

A frequent application of the nanoscratch technique is to estimate hardness of ultrathin films when substrate effects are encountered with the nanoindentation technique. A model based on the work of Goddard and Wilman, which assumes a rigid-plastic behavior of the deformed surfaces, is commonly used for the determination of hardness from scratch tests, yet it overestimates the hardness of materials by as much as a factor of three at very shallow indentation depths on the order of 1–10 nm. The Goddard and Wilman model was extended in this paper to include the effects of the component of the shear stress tangential to the meridianal plane and the elastic recovery of the plastically deformed surfaces assuming elastic-perfectly-plastic material behavior. The proposed model was subsequently verified by performing nanoscratch experiments on fused quartz, which is homogeneous and isotropic with no known surface layers and with known hardness. The hardness was calculated using both the model based on the work of Goddard and Wilman and the extended model. The hardness calculated using the extended model was in very close agreement with the accepted value of bulk hardness of fused quartz over the range of scratch depths tested, showing the importance of the effects of elastic recovery and interfacial shear stress. The model was further verified for the case of a pure aluminum sample and the native thin film coating of alumina that forms on the surface upon air exposure.

The effects of the electrokinetic behavior of abrasive ceria particles suspended in an aqueous medium and the deposited plasma-enhanced tetraethylorthosilicate (PETEOS) and chemical vapor deposition (CVD) Si3N4 films on chemical mechanical planarization (CMP) for shallow trench isolation were investigated. The colloidal characteristics of ceria slurries, such as their stability and surface potential, in acidic, neutral, and alkaline suspensions were examined to determine the correlation between the colloidal properties of ceria slurry and CMP performance. The surface potentials of the ceria particles and the PETEOS and CVD Si3N4 films in an aqueous suspending medium were dependent on the pH of the suspending medium. The differences in surface charges of ceria particles and the PETEOS and CVD Si3N4 films have a profound effect on the removal rate and oxide-to-nitride selectivity of CMP performance.

A high-resolution laser-assisted loading dilatometer was applied for the precise measurement of radial and axial strain rates under different uniaxial loads, using alumina as a model material. As a continuous application of an external load can lead to an anisotropic microstructure, a discontinuous hot forging technique was utilized to determine the viscous Poisson's coefficient. In these studies, samples were presintered to different densities and only then were hot-forging tests performed. The result provides an isotropic viscous Poisson's coefficient, which increases smoothly between 0.21 and 0.42 within the accessible density range. Combined with the uniaxial viscosity measured before using the same technique, the hydrostatic sintering stress, bulk viscosity, and shear viscosity as a function of density are now available for solid-state sintering. A comparison of the experimentally obtained results with several theoretical models is included.

Thin separation by implanted oxygen substrates are attractive candidates for low-power, low-voltage electronic devices and can be obtained by low-dose, low-energy oxygen–ion implantation. We report in this study a variation of the process parameters that have never been investigated before, particularly for implantation with a high current density implanter. Characterization of the sample sets by transmission electron microscopy, secondary ion mass spectroscopy (SIMS), and Rutherford backscattering spectrometry (RBS) shows an optimum dose of 3.0 to 3.5 × 1017 O+/cm2 at 100 keV for forming a continuous buried oxide (BOX) layer compared to 2.5 × 1017 O+/cm2 at 65 keV. At this optimum condition for 100 keV, the thickness of Si top layers and BOX layers is in the range of 175–185 nm and 70–80 nm, respectively. Analysis of the breakdown voltage of small area capacitors shows a breakdown field in the range of 6.0–7.0 MV/cm, which is adequate for low-power, low-voltage devices. SIMS analysis shows that the maximum oxygen concentration of as-implanted samples is located at depths of 160 and 240 nm for the implantation energy of 65 and 100 keV, respectively. A significant redistribution of oxygen occurs at temperatures above 1300 °C during the ramping process. RBS analysis showed that a high-quality crystalline Si layer was produced after annealing at 1350 °C for 4 h. The defect density determined by the chemical etching method was found to be very low (<300 defects per cm2) for all samples with a dose range of 3.0 × 1017 O+/cm2 to 6.0 × 1017 O+/cm2 implanted at 100 keV. However, a 65 keV sample with a dose of 4.5 × 1017 O+/cm2 contains about 109 defects per cm2. The larger defect density in the 65-keV sample may be due to the shift of oxygen depth distribution toward the surface, resulting in easier defect extension during the annealing process. The oxide precipitates in the Si overlayer play a key role in defect reduction by blocking the extension of dislocations to the surface.

Aligned single-walled carbon nanotube (SWNT) ropes show excellent field-emission performance due to their high aspect ratio and sound alignment. In this study, the effect of geometrical parameters, such as cathode-anode distance and the height of SWNT ropes on the field-emission properties of SWNT ropes was investigated. It was found that the cathode-anode distance influences the emission properties, such as the turn-on field Fto and threshold field Fthr, of SWNT ropes, and the turn-on and threshold fields are marginally decreased at relatively larger gaps between the SWNT emitter tip and the anode plane. It was also found that the emission properties of SWNT ropes are improved by increasing the rope length, at least in the present experimental range. A possible two-step field amplification model was proposed to explain this length effect of SWNT ropes. The estimated results show that the local field at the tip of SWNT ropes, which causes a certain emission-current density, seems not to change with the cathode-anode distance, and the effective emission area of the SWNT rope is much smaller than the apparent cross-sectional area of the SWNT rope. The results obtained suggest that it is possible to optimize the performance of SWNT rope-based cold cathode by adjusting geometrical parameters of SWNT rope emitters.

A high-resolution transmission electron microscope was used to study the interfacial and twin boundary structure of nanostructured Cu–Ag filamentary composites. Copper matrix and silver filaments have the orientation relationship {111}Cu∥{111}Ag and 〈111〉Cu∥〈111〉Ag. In some regions, twin bands propagated through the silver filaments with some boundary steps at the matrix/filament interface, and the silver filament appeared to be kinked in the twin band in the same direction as the twinning shear. This suggests that twins propagated after the formation of silver filament, and twin bands were deformation twins. At the matrix/filament interface, misfit interface dislocations were introduced periodically to relieve the misfit strain. The distance between interfacial misfit dislocations along the matrix/filament interface in the longitudinal section was measured to be 1.88 nm, which is in good agreement with that (1.81 nm) calculated based on lattice misfit. In Cu–Ag nanocomposites, the spacing between Moire fringes was found to be quite close to that between interfacial misfit dislocations.

A uniform deposition of a Sn–Zn alloy deposit was achieved by pulse plating. Apparently, the relative composition of Sn and Zn in the deposit was affected by the bath compositions and pulse condition. A pulse-plating condition of 99.9 ms on-time and 1.0 ms off-time gave rise to a eutectic Sn–Zn deposit, with a eutectic temperature of 198.8 °C (as analyzed by differential scanning calorimetry) and a uniform composition distribution across the deposit. A mechanism for explaining the pulse-deposition behavior of the Sn–Zn eutectic deposit was proposed. A longer off-time period, 99.9 ms versus 0.1 ms, resulted in a nodular, yet thinner deposit.

The Pr55–xAl12+xFe33–yCuy (0 ≤ x ≤ 5, 0 ≤ y ≤ 8) bulk metallic glasses (BMGs) 5 mm in diameter and 100 mm in length were prepared by copper mold suction casting. Hysteresis loops of the Pr55–xAl12+xFe33–yCuy BMGs and the corresponding Pr55Al12Fe30Cu3 crystallized alloy were measured, and the results showed that the Pr55–xAl12+xFe33–yCuy BMGs are hard magnetic, while the completely crystallized Pr55Al12Fe30Cu3 alloy is paramagnetic at room temperature. The thermal behavior and crystallization of the Pr55Al12Fe30Cu3 BMG were studied by differential scanning calorimetry, and the results indicated that the Pr-based BMG has obvious glass transition and a wide supercooled liquid region up to 75 K. The crystallization activation energy for the Pr55Al12Fe30Cu3 BMG is much smaller than that of Zr–Ti–Cu–Ni–Be BMG.

Three-dimensional photonic crystals with a diamond structure, which are composed of the TiO2-based ceramic particles dispersed in an epoxy lattice, were fabricated by stereolithography. The diamond structure showed a photonic band gap in the 14.3–17.0 GHz range along the Γ-K 〈110〉 direction, which is close to the band calculation using the plain wave expansion method. Two types of lattice defects—air cavity and dielectric cavity—were introduced into the diamond structure by removing a unit cell of diamond structure or inserting a block of the lattice medium into the air cavity. The transmission of millimeter waves affected by multiple reflections at the defects was measured in the photonic band gap. Resonant frequencies in the defects were calculated and compared with the measurement results.

The type and magnitude of stress in electroless Ni–Cu–P deposits on Al were manipulated by controlling the concentration of saccharin in the plating solution. Tensile, zero, and compressive stress of the electroless Ni–Cu–P deposits was obtained with 0, 8, and 10 g/l saccharin for studying the effect of stress on the diffusion and crystallization behavior of the deposit. The effect of stress on the diffusion behavior of Cu, Ni, and Al elements during annealing was investigated. Interdiffusion between Al and Ni in an amorphous Ni–Cu–P/crystal Al diffusion couple is abated by the effects of amorphous structure, atomic affinity, and backstress. Therefore, the effect of stress on diffusion is manifested by Cu elemental diffusion. The tensile stress promotes the formation of Ni3P and the diffusion of Cu into the substrate.

We report the growth of titanium nitride microcolumns under multipulse Nd:yttrium aluminum garnet (λ = 1.064 μm, τ ∼ 300 ns, ν = 30 kHz) laser irradiation of titanium targets in nitrogen atmosphere. The laser intensity value was chosen below the single-pulse melting threshold of titanium. The evolution with the number of laser pulses of the target morphology, crystalline state, and chemical composition at the surface as well as in depth were investigated by scanning electron microscopy, x-ray diffractometry, Raman spectroscopy, and wavelength dispersive x-ray spectroscopy. Under the action of the laser pulses, during progressive surface nitridation, an initial rippled morphology developed, which evolved with further irradiation to TiN microcolumns. In-depth investigations showed a granular zone beneath the surface consisting of rutile and anatase phase TiO2, followed by a compact needlelike layer of titanium until the interface with the unaffected target material.

Effects of TiO2 addition on the conduction mechanism of buried resistors in low temperature cofired ceramics were investigated. Remarkable increases in electrical resistivity and attractive decreases in the temperature coefficient of resistance were observed by the addition of TiO2 for all ratios of RuO2/glass investigated. Such significant effects can be attributed to a larger separation observed between RuO2 particles. The results were compared with the calculated data from theoretical model of tunneling barrier, showing that good agreement could be obtained. In addition, while the distance separation was taken into account as a fixed constant, it was found that the resistivity of buried resistor decreased with increasing TiO2 contents in the glass at higher weight ratios of TiO2/glass. This result implies that a substitution takes place due to the Si+4 displacement by Ti+4 in the glass, resulting in a looser network structure and a lower resistivity value.

A novel Ag/mica compressive seal was thermally cycled between 100 °C and 800 °C in air to evaluate its stability. The novel Ag/mica compressive seal was composed of a naturally cleaved Muscovite mica sheet and two thin silver layers, and was reported in a previous study to have very low leak rates at 800 °C. In the present study, we examined the thermal cycle stability of the Ag/mica-based compressive seals pressed between mating couples with large and small mismatch in thermal expansion. For comparison, thermal cycling also was conducted on plain mica as well as plain silver only. In addition, the results were compared with published data of a similar mica seal using glass instead of Ag as the interlayers. For mating materials of large mismatch in thermal expansion coefficient (CTE; Inconel/alumina), the Ag/mica seal showed lower leak rates than the plain mica. For mating materials of small mismatch in CTE (SS430/alumina), the leak rates were similar for both the Ag/mica and the plain mica seal. Scanning electron microscopy was used to characterize the microstructure of the mica after thermal cycling. Microcracks, fragmentation, and wear-particle formation were observed on the mica and were correlated to the leak behavior. Overall, the novel Ag/mica seals present good thermal cycle stability for solid-oxide fuel cells, although the leak rates were greater than the corresponding mica seals with glass interlayers.

Nanoindentation testing has been used to measure the hardness and elastic modulus of Ag3Sn, Cu6Sn5, and Cu3Sn intermetallics, as well as Sn–Ag–Cu solder and pure Sn and Cu. The intermetallics were fabricated by solid-state annealing of diffusion couples prepared from a substrate (Cu or Ag) and a solder material (Sn or Sn–Ag–Cu solder), providing geometries and length scales as close as possible to a real solder joint. Nanoindentation results for the intermetallics, representing penetration depths of 20–220 nm and loads from 0.7 to 9.5 mN, reveal elastic/plastic deformation without evidence of fracture. Measured hardness values of Cu6Sn5 (6.5 ± 0.3 GPa) and Cu3Sn (6.2 ± 0.4 GPa) indicate a potential for brittle behavior, while Ag3Sn (2.9 ± 0.2 GPa) appears much softer and ductile. Using a bulk Cu6Sn5 sample, Vickers hardness testing revealed an indentation size effect for this compound, with a hardness of 4.3 GPa measured at a load of 9.8 N. An energy balance model is used to explain the dependence of hardness with load or depth, where the observation of an increasing amount of fracture with applied load is identified as the primary mechanism. This result explains discrepancies between nanoindentation and Vickers results previously reported.

Silicon nitride–tungsten (Si3N4–W) composites were fabricated by reduction of tungsten boride under hot-press sintering in a nitrogen atmosphere. The fabricated composite consisted of mainly β–Si3N4 and W. The Si3N4 matrix grains were composed of an elongated and bimodal structure similar to conventional Si3N4. The mechanical properties of the composites in terms of fracture toughness and strength were almost the same as those of a monolithic Si3N4 produced under the same sintering conditions. The sliding wear properties of the composites were evaluated using a ball-on-disk machine under unlubricated sliding conditions against a commercial Si3N4 ceramic ball. The tungsten (W) content had a significant effect on the composite wear properties. In particular, for a composite disk with a W content of 8 vol% the specific wear rate of the opposing ball was decreased around ten times compared to the monolithic Si3N4. The composites had higher wear resistance compared with the conventional silicon nitride, which was attributed to the formation of debris consisting of W, Si, and O. The debris restricted the adhesion of the two surfaces.

Thermoset acrylic–melamine resins are widely used for automobile exterior coatings. These materials are formulated by reacting an acrylic polyol with an alkylated melamine. Because the reactions are reversible, acrylic–melamine coatings tend to hydrolyze during exposures in moist environments. During hydrolysis, water in the coating film is consumed. To keep the moisture content in the film in equilibrium, water must be transported from regions of high water concentration to regions of low water concentration. An approach based on Fourier transform infrared (FTIR) spectroscopy analysis of the coating degradation fitted to a transport model is presented to estimate the diffusion coefficients and velocities of water transport during the hydrolysis of an acrylic–melamine coating exposed to different relative humidities (RHs). Theoretical prediction agreed well with the experimental FTIR data of coating hydrolytic degradation. Generally, both the diffusion coefficient and velocity of water transport in the coating increased with increasing RH. Since water transport resulting from the hydrolysis reactions is a very slow and complex process, the approach presented here provides a viable means for obtaining valuable data for quantitative analyses of coating hydrolytic degradation at different RHs.