Sn whiskers can form at room temperature on the agglomerated flakes produced by mechanical alloying (MA) of Ti, Sn, and C powders, whether the flakes are stored in air or water. The Sn whiskers forming in air are tens of micrometers to several centimeters in length and 0.5 to ∼10 μm in diameter. Whereas a large amount of Sn polyhedra forms on the flakes that are stored in water, a small amount of Sn whiskers forms on the polyhedra. The driving force for Sn whisker formation is the compressive stress induced by mechanical alloying (MA) and oxidation. The mechanism about the spontaneous growth of metal whiskers is discussed.

The infiltration behavior of compacts of SiC particles in two surface conditions, as-received and thermally oxidized, was investigated by using pure Al and Al-12wt%Si as infiltrating metals. Analysis of the threshold pressure for infiltration revealed that the process is governed by the same contact angle for all different systems, no matter the metal or particle condition. This leads to the conclusion that oxidation does not modify the wetting characteristics of the particles, most probably because they are already covered by a thin native oxide layer that remains unaltered in processing routes involving short contact times and low temperatures, such as actual conditions of pressure infiltration at 700 °C.

The response of a mononuclear, heteroleptic titanium alkoxide [(OPy)2Ti(4MP)2, where OPy = pyridinecarbinol; NC5H4(CH2O) and 4MP = 4-mercaptophenol; OC6H4(SH)] to ultraviolet (UV) irradiation in dilute solution and in solid-state samples has been measured. Vibrational spectroscopy [Fourier transform infrared (FTIR) absorption and Raman scattering] was used to monitor changes in molecular structure upon exposure to 337.1- and 365-nm light. Assignment of spectral features to vibrational modes of the molecule was aided by a normal-mode analysis of the energy-minimized molecular structure within a density-functional theory framework. Photoinduced decreases in peak areas were observed in both FTIR spectra of the precursor solutions and Raman data collected from solution-cast films of the precursor material. These changes were associated with vibrational modes localized at the 4MP ligands. Conversely, no significant modification of vibrational structure associated with the OPy moiety was observed under the excitation conditions examined. In a related study, thin films of the precursor were cast, sampled, and irradiated with UV light in scintillation vials under hydrated air (40% relative humidity) and dry Ar to evaluate the influence of local atmospheric composition on the photoresponse. An increase in the magnitude of photoinduced vibrational changes was observed in the moist-air environment, again associated primarily with the 4MP ligand. The results support an interpretation of these structural changes in terms of a preferential enhancement of hydrolysis at the 4MP site under these conditions. These findings are discussed in the context of an optically driven molecular assembly strategy based on the photoinitiation of intermolecular bonding at selected sites about the metal center.

The quasi-static compressive deformation behavior of a Vitreloy 1 bulk metallic glass (BMG) with an aspect ratio of 0.25 was investigated. It is found that the friction and the confinement at the specimen–loading platen interface will cause the dramatic increase in the compressive load, leading to higher compressive strength. In particular, the BMG specimens show great plastic-deformation ability, and plenty of interacted, deflected, wavy, or branched shear bands were observed on the surfaces after plastic deformation. The formation of the strongly interacted, deflected, wavy, or branched shear bands can be attributed to the triaxial stress state in the glassy specimens with a very small aspect ratio.

Vickers indentations of ZnO crystals grown by the hydrothermal method were studied by cathodoluminescence. The defects induced by indentation influenced the luminescence spectrum, indicating the generation of non radiative recombination centers and a band close to the first phonon replica of the free exciton, in the surrounding area near the indentation. The possible nature of the defects responsible for such band is discussed. A comparison with polishing induced damage is also presented.

Copper was supplied to Sn–3.5Ag by electroplating Cu/Ni double under-bump metallization (UBM), and the amount of Cu was controlled by varying the Cu UBM thickness. Supposed Cu contents in the solder were; 0.2, 0.5, and 1.0 wt%, respectively, and the solder joint microstructure was investigated after 1, 5, and 10 reflows. In the case of specimens with 0.2 and 1.0 wt% Cu, only one type of intermetallic compound (IMC) formed, either (Cu,Ni)6Sn5 or (Ni,Cu)3Sn4, while two types formed in specimen with 0.5 wt% Cu. No correlation could be found between the solder joint microstructure and the ball shear test. However, drop test results showed two opposite trends. The drop resistance of 0.2 and 1.0 wt% Cu specimens was quite good initially but degraded dramatically with multiple reflows, in contrast to that of the 0.5 wt% Cu specimen, which was very poor after one reflow but improved substantially later on. The former was ascribed to thickening of IMC during reflow, while the latter was related to (Ni,Cu)3Sn4 thickening beneath (Cu,Ni)6Sn5 and subsequent spalling of (Cu,Ni)6Sn5 from (Ni,Cu)3Sn4.

A comprehensive study of the sensitivity characteristics associated with the determination of the elasto-plastic properties of a large number of materials using several combinations of dual, triple, and quadruple sharp indentation, and spherical indentation illustrates that: (i) The lowest sensitivity to the determination of plastic properties is observed for the indenter combination that corresponds either to the largest difference in the corresponding representative stresses or the largest difference in the indenter apex angles. (ii) The triple or quadruple sharp indenter combinations considered in the present study do not show a significant improvement in the sensitivity characteristics when compared to that of the dual sharp indentation. (iii) In the determination of plastic properties through spherical indentation where two representative stresses are invoked, the highest and the lowest sensitivity, respectively, are observed for the combinations in which the differences in the representative stresses are the lowest and the highest. The sensitivity is further reduced if a large number of representative stresses are considered for the reverse analysis.

We have measured the porosity in thin films of lithium fluoride (LiF), magnesium fluoride (MgF2), barium fluoride (BaF2), and calcium fluoride (CaF2) as a function of the substrate temperature for films deposited by thermal evaporation onto glass substrates. The amount of porosity in the thin films was measured using an atomic force microscope and a quartz crystal thickness monitor. The porosity was very sensitive to the substrate temperature and decreased as the substrate temperature increased. Consistent behavior was observed among all of the materials in this study.

The electrochemical corrosion behavior of Sn–XAg–0.5Cu alloys in 3.5% NaCl solution was examined using potentiodynamic polarization techniques. The Ag content in the alloy was varied from 1 to 4 wt%. The polarization curves obtained for the alloys show an active–passive transition followed by a transpassive region. Sn–XAg–0.5Cu alloys with higher Ag content (>2 wt%) show a strong tendency toward passivation. The passivation behavior has been ascribed to the presence of both SnO and SnO2 on the anode surface. Increase in Ag content from 1 to 4 wt% results in a decrease in the corrosion-current density (Icorr) and linear polarization resistance (LPR) of the alloy. Nevertheless, the corrosion potential (Ecorr) shifts toward negative values, and a decrease in corrosion rate is observed. The presence of Cl− ion initiates pitting and is responsible for the rupture of the passive layer at a certain breakdown potential. The breakdown potential (EBR) decreases and shifts toward more noble values with increase in Ag content in the alloy. Surface analyses by x-ray photoelectron spectroscopy (XPS) and Auger depth profile studies confirmed the formation of both Sn(II) and Sn(IV) oxides in the passive layer.

We studied the effect of anisotropic pore morphology on the fatigue behavior and fracture surface of lotus-type porous copper, which was fabricated through unidirectional solidification in pressurized hydrogen and argon atmospheres. The fatigue strength at finite life is closely related to the pore morphology. The fatigue strength decreases with increasing porosity, and the strength depends on applied-stress direction. The fatigue life is the longest in the direction parallel to the longitudinal axis of cylindrical pores. The fatigue strength at finite life is proportional to the ultimate tensile strength and can be expressed by a simple power-law formula. Anisotropic pores affect the fracture surface of lotus copper; crack-initiation site depends on applied-stress direction, and the anisotropic shape pores affect the direction of crack propagation and final fracture surface.

Thermoelectric power generation is a promising method for harnessing waste thermal energy, especially in the temperature range between 500 and 800 K. It is necessary to improve the performance of thermoelectric materials for the realization of the power generation. Dispersion of nanoparticles such as fullerenes is expected to induce phonon scattering that decreases thermal conductivity of materials, and application to thermoelectric materials may lead to improved properties. In the present study, the n-type Co0.92Ni0.08Sb2.96Te0.04 thermoelectric compound was synthesized, and the thermoelectric properties were evaluated. Furthermore, the fullerene particles were sufficiently mixed with the thermoelectric compound powder by the mechanical grinding method, and influences of the fullerene additions to the compound were investigated. The dispersion of fullerene particles in the n-type Co0.92Ni0.08Sb2.96Te0.04 compound was conducted through the planetary ball milling method to disentangle agglomerates of the fullerene and to disperse the particles in the thermoelectric compound matrix. The thermal conductivity decreased with an increase in fullerene content, and the maximum in dimensionless figure of merit ZT was 0.62 at 800 K for 1 mass% fullerene addition. This was 28% higher than that of fullerene-free sample.

The influence of different raw material mixtures on β-sialon (Si6−zAlzOzN8−z, 1 ⩽ z ⩽ 4) formation through mechanical activation coupled combustion synthesis (MA-CS) was investigated in low nitriding atmosphere of 1 MPa without diluent inclusions. The MA-CS performed for the first time on sialon raw materials with milling time of 18 min obtained sialons more than three times as pure as those obtained by CS of mixtures ball milled to 1 h (z = 3). The starting materials containing silicon, aluminum, and alumina (z = 4) after MA-CS had an increment of sialon amounts up to 88 mass%.

We have investigated the electrical resistivity of (0001)-oriented Tin+1ACn (A = Si, Ge, Sn, n = 1–3) thin films deposited by magnetron sputtering onto Al2O3(0001) substrates at temperatures ranging from 500 to 950 °C. Four-point-probe measurements show that all films are good conductors with resistivity values of ∼21–51 μΩ cm for Ti–Si–C films, ∼15–50 μΩ cm for Ti–Ge–C films, and ∼46 μΩ cm for Ti2SnC. We find a general trend of decreasing resistivity with decreasing n for the Ti–Si–C and Ti–Ge–C systems due to the increased metallicity obtained with increasing density of A-element layers. We also show that crystalline quality and competitive growth of impurity phases affect the measured resistivity values. The effect of a given impurity phase largely depends on its location in the sample. Specifically, a TiCx layer in the center of the film constricts the current flow and results in an increased measured resistivity value. However, TiCx transition or seed layers at the substrate–film interface as well as surface segregation of Ge and Ti5Ge3Cx (for Ti–Ge–C) have only little effect on the measured resistivity values. For the Ti–Sn–C system, the resistivity is mainly influenced by the segregation of metallic Sn, yielding a wide spread in the measured values ranging from 20–46 μΩ cm, in the order of increased film purity.

The effects of the molecular weight and concentration of poly(acrylic acid) (PAA) with different primary abrasive sizes in ceria slurry on the nitride film loss, removal rate, film surface roughness, and removal selectivity of SiO2-to-Si3N4 films were investigated by performing chemical mechanical polishing (CMP) experiments using blanket and patterned wafers. In the case of the blanket wafers, we found that for a lower PAA molecular weight, the removal selectivity of SiO2-to-Si3N4 films increased more significantly with increasing PAA concentration in slurry containing a larger primary abrasive size. For the patterned wafers, with a higher PAA molecular weight in the ceria slurry suspension, the erosion of the Si3N4 film was less, but the removed amount was also smaller, and the surface roughness became worse after CMP. These results can be qualitatively explained by the layer of PAA adsorbed on the film surface, in terms of electrostatic interaction and rheological behavior.

Chromium oxide coatings were deposited on low-carbon steel by radiofrequency reactive magnetron sputtering at different oxygen flux values. X-ray diffraction, x-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy were used to investigate the microstructure of chromium oxide coatings. Varying oxygen flux changed the coating microstructure; as with increasing oxygen flux the chromium oxide coating undergoes amorphous-to-crystalline transformation. The coating developed strong (300) texture at higher oxygen flux. Hardness, elastic modulus, wear resistance, and adhesion were investigated by nanoindentation and pin-on-disk tests. With changes in the coating microstructure as a function of increased oxygen flux, hardness, elastic modulus, and wear resistance were improved, but its adhesion was weakened.

Compression tests were conducted on the as-cast Zr58Ni13.6Cu18Al10.4 metallic glass at room temperature. The effect of nanocrystalline Ni-15%Fe coating (mean grain size: ∼10 nm) on mechanical properties was investigated. The results demonstrate that the strength, elastic limit, Young’s modulus, and fracture geometry and morphology are not affected by this nanostructured coating. However, the compressive plastic strain increased noticeably when the specimens were coated with a layer of nanocrystal, which is attributed to the increased shear band density. The high shear band density is suggested to be due to the inhibition of shear band operation by nanocrystalline coating. The significance of this study is that a new strategy was developed to improve the ductility of bulk metallic glasses.

A facile solution-based processing route using standard spin-coating deposition techniques has been developed for the production of reliable capacitors based on lead lanthanum zirconate titanate (PLZT) with active areas of ⩾1 mm2 and dielectric layer thicknesses down to 50 nm. With careful control of the dielectric phase development through improved processing, ultrathin capacitors exhibited slim ferroelectric hysteresis loops and dielectric constants of >1000, similar to those of much thicker films. Thus, it has been demonstrated that chemical solution deposition is a viable route to the production of capacitor films which are as thin as 50 nm but are still macroscopically addressable with specific capacitance values >160 nF/mm2.

The evolution of the kinetic energy distribution of photoelectrons from a cube-oriented aluminum sample during tensile deformation was probed with a retarding field energy analyzer. Because of the anisotropy of the aluminum work function, the electron-energy distribution is altered as the area fractions of the major surface planes change during deformation. In cube-textured aluminum, deformation reduces the {100} area fraction and the relatively low energy electrons from these surfaces. Conversely, the {110} and {111} area fractions and the relatively high energy electrons from these surfaces both increase. These changes are quantitatively consistent with texture analysis by electron backscattered diffraction (EBSD). They reflect deformation-induced production of {111} surfaces by slip and the exposure of {110} surfaces by grain rotation. Photoelectron kinetic energy measurements supplement EBSD measurements and are readily acquired in real-time.

Li2MgN2H2 can reversibly store more than 5.5 wt% hydrogen. However, the high activation energy of hydrogen desorption poses a kinetic barrier for low-temperature operation. In this work, the composition of the Li–Mg–N–H system has been modified by the partial substitution of Mg or Li by Na. The changes in structure and hydrogen absorption/desorption kinetics have been investigated. It was found that the peak temperature for hydrogen desorption was decreased by ∼10 °C, and that the hydrogen absorption/desorption isotherms were also significantly changed. Furthermore, the activation energy calculated by the Kissinger’s approach was reduced after the substitution of Mg or Li by Na. In addition, the different dehydrogenation structures were detected at different molar ratios of Mg, Li, and Na.

Ordered arrays of Ta2O5 nanodots were prepared using anodic aluminum oxide (AAO) as a template to support localized oxidation of TaN. Films of TaN (50 nm) and Al (1.5 μm) were deposited successively on p-type Si wafers and followed by a two-step anodization process at 40 V using oxalic acid as the electrolyte. The first anodization promoted growth of irregular AAO from overlying Al film. After chemical etching, the second anodization was performed to develop well-organized AAO channels and initiate oxidation of underlying TaN film to form tantalum oxide nanodots at the AAO pore bottoms. X-ray photoelectron spectroscopy results confirmed the chemical nature of nanodots as stoichmetric Ta2O5. X-ray diffraction demonstrated the amorphous characteristic of Ta2O5. As shown in field-emission scanning electron microscopy and transmission electron results, the Ta2O5 nanodots exhibited a hillock structure 80 nm in diameter at the bottom and 50 nm in height. We also synthesized 30-nm nanodots by adjusting AAO formation electrochemistry. This demonstrates the general applicability of the AAO template method for nanodot synthesis from nitride to oxide at a desirable size.