The in-flight modification of titanium carbide powders was carried out in radio-frequency (rf) inductively coupled plasmas. The powders were partially melted and evaporated, and then subjected to modifications in morphology, size, and chemical composition. Both the Ar–H2 and Ar–N2 plasma treatments induced the formation of carbon-site vacancies in titanium carbide. The mixing of NH3 to Ar–H2 plasma at the plasma tail, and the Ar–N2 plasma treatment resulted in the partial substitution of carbon by nitrogen. The variation in physical and chemical modification was discussed compared with the predictions by the thermochemical analysis, and the numerically obtained heat transfer of our preceding paper.

Electrodeposited Cu/Ni multilayers with different modulation lengths Λ = 4–18 nm were examined by means of x-ray diffraction and transmission electron microscopy. Preferred orientations of [111], [110], and [001]-types, as determined from relative x-ray diffraction peak intensities, were seen in the multilayers. By means of computer simulations of the measured x-ray diffraction spectra, several parameters of the multilayers, such as Λ-values and fluctuations ΔΛ, as well as lattice strain, were determined. Multilayers having large Λ were found to be fully relaxed due to interfacial dislocation formation. In short Λ [001]-texture multilayers partial strain relaxation occurs, probably due to the incorporation of Cu into the Ni layers. Both of the processes lead to the diffuse Cu/Ni interfaces. Short wavelength multilayers with a [111]-preferred orientation were almost fully strained. The importance of the [111]-texture in the improvement of mechanical strength of Cu/Ni multilayers resulting from its enhanced ability for stain accommodation is discussed.

Gold particles smaller than 2 nm in diameter were grown in glass. Their optical absorption spectrum did not show the usual plasma absorption band for gold particles; this band was spread by the small particle size. The absorption spectrum was calculated from the bulk optical properties of gold, modified for the small particle size; there was good agreement between calculated and measured spectra. The smallest particles containing from 20 to 40 gold atoms showed a λ−4 dependence of absorption on wavelength λ. This result implies that the absorption in these particles was entirely from free electrons at wavelengths above 0.3 μm.

Dispersions of nanometer-sized In particles embedded in an Al matrix (10 wt. % In) have been synthesized by ball milling of a mixture of Al and In powders. The as-milled product was characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HREM), respectively. It was found that In and Al are pure components immiscible with each other, with nanometer-sized In particles dispersively embedded in the Al matrix. The melting behavior of In particles was investigated by means of differential scanning calorimeter (DSC). The calorimetric measurements indicate that both the melting point and the melting enthalpy of the In nanoparticles decrease with increasing milling time, or refinement of the In particles. Compared to its bulk melting temperature, a melting point depression of 13.4 K was observed when the mean grain size of In is 15 nm, and the melting point depression of In nanoparticles is proportional to the reciprocal of the mean grain size. The melting enthalpy depression was interpreted according to the two-state concept for the nanoparticles. Melting of the interface was deduced to be an exothermal process due to its large excess energy/volume.

Microwave plasma chemical vapor deposition (MWPCVD) process has been used to grow diamond thin films on silicon substrates from CH4–H2 gas mixture. Bias-enhanced nucleation (BEN) pretreatment has been used to increase the density of diamond nuclei. Various species in the CH4–H2 plasma have been identified using optical emission spectroscopy (OES), and their effect on the film microstructure has been studied. During the pretreatment process the emission intensities of CH, CH+, C2, H, and H2* species have been found to increase significantly for a negative dc bias voltage |VB| > 60 V. The higher concentration of excited species and the associated effects play a significant role in the growth process. A very thin layer of a-C containing predominant sp3 bonded carbon species in the initial stages of the growth is found to be present in these films. The microstructure of the films has been found to be very sensitive to the biasing conditions.

Copper oxide powders were prepared by the spray pyrolysis of copper nitrate solutions over a range of temperatures (400–1300 °C) and residence times (3–7 s). Phase-pure [by x-ray diffraction (XRD)] copper (I) oxide was obtained at 800–1300 °C in an inert (nitrogen) atmosphere. The particles varied from smooth, solid spheres at 1300 °C to irregularly shaped and hollow particles at 800 °C with dense particles of Cu2O being made only at 1000 °C or higher. The particles were polycrystalline with an average crystallite size of 42 nm at 800 °C, while at 1000–1200 °C, the particles were single crystals. Spray pyrolysis in forming gas (7% H2–N2) atmosphere at 500–700 °C gave Cu while spray pyrolysis in air yielded CuO over 800–1000 °C and a mixture of Cu2O/CuO at 1200 °C. These results show that solid, phase-pure Cu2O particles can be produced by aerosol-phase densification at temperatures below its melting point (1235 °C).

The growth of NaLa(WO4)2 crystals has been carried out by the hydrothermal method at fairly low P-T conditions. The crystal morphology has been studied with respect to the growth parameters. The crystals obtained were characterized by various techniques such as x-ray diffraction (XRD), differential thermal analysis (DTA), and infrared (IR) spectroscopy.

A set of simple and accurate formulae for the first four moments of nuclear and electronic energy losses is proposed. A new variable is introduced to include the finite maximum-impact-parameter effect in the nuclear stopping process, which is assumed to be infinite in most studies. A critical energy at which the electronic energy loss is equal to the nuclear energy loss is also defined. It determines whether the nuclear or the electronic stopping process is the dominant mechanism in terms of incident-ion energy. The critical energy increases for heavy ions implanted in heavy target materials during the first moment of energy loss. The second moment of electronic energy loss is important only for light ions implanted at high ion energies. The third and fourth moments of nuclear energy loss are much larger than those of the electronic energy loss for all ion-target combinations. Theoretical predications of the projected ranges and range stragglings for gold ions implanted in carbon films are close to the experimental data when these proposed four moments of nuclear and electronic energy losses are considered.

A novel pressureless reaction sintering process is presented for the fabrication of Al2O3-aluminide alloys (3A). Compacts of intensively milled metal oxide-aluminum mixtures are heat-treated in vacuum or inert atmosphere such that the exothermic reactions take place in a controlled manner essentially at temperatures below the melting point of Al. Dense, homogeneous microstructures were obtained with a variety of Al2O3-matrix systems with interpenetrating networks of aluminides of Ti, Fe, Nb, Mo, Zr, Ni, etc. By adding modifiers in the form of oxides or metals, volume and phase composition as well as properties can be tailored in a wide range.

Carbon-filled polyethylene composites were fabricated and tested to establish the practical lower limit of their electrical resistivity at room temperature and to investigate the trade-offs between low resistivity and the magnitude of the resistance anomaly (i.e., a large positive temperature coefficient of resistivity) that appears when such composites are heated through the polyethylene crystalline melting transition. Carbon blacks with large particle size and low surface area provided low-resistivity composites having large resistance anomalies. The largest resistance anomalies were found in composites that were well mixed, but the room-temperature resistivity also increased in composites that were cycled repetitively through the crystalline-melting transition. A mixture of carbon blacks of two different sizes provided a lower resistance than was found in a material with the same fill of only the coarser black. By controlling the composition and the processing, composites were made with room-temperature resistivities lower than 0.2 ohm cm and resistance changes of at least 2 orders of magnitude. A resistance change of as much as 5 orders of magnitude was obtained for composites with room-temperature resistivities of only 1 ohm cm.

A hexacarbonyl of chromium and molybdenum [(Cr, Mo) (CO)6] was used as an oxycarbide source for the coating on stainless steel 304 (SS304) at temperatures from 175 °C to 450 °C. Hardness of the films was determined from a microindentation technique through a similar calculation after Thomas (1987). Intrinsic hardnesses of the films formed at low and medium temperatures were determined to be 8.61 and 2.75 GPa, respectively. Both of them are larger than that of SS304 substrate, 1.75 GPa. Adhesive strength of the films was measured by the scratching test. The results reveal that the adhesive strengths of the films formed at low, medium, and high temperatures are 2.8 N, 37.6 N, and 36.0 N, respectively. Two different fracture modes after scratching were found for the films obtained at various temperature regions. A spalling-off type or a deformation failure with many cracks and deformation bands beside the striation was found.

Techniques from the field of materials science and engineering were utilized to examine the mechanical effects of dark pigment in exoskeleton material on the distal portion of stone crab, Menippe mercenaria, chelae. We made specimens from dark-and light-colored exoskeleton material to measure hardness and fracture toughness. The results from these tests showed the dark material to be much harder and tougher than light-colored material from the same crab chela. Scanning electron microscope photographs are presented to document the microstructure and level of porosity. We think that the structural difference in material properties is due to the lower level of porosity and phenolic tanning in dark material and that this tanning caused the dark color and filling of porosity. The exoskeleton structure is a laminated organic-inorganic structure which can serve as a model for self-healing structures.

Glass microballoons (GB) of about 1 μm in diameter were prepared by ultrasonic spray pyrolysis from sodium silicate solution. A silica-rich type of glass microballoons (SB) was prepared by acid treatment of GB. The structural changes of both microballoons with thermal treatment up to 973 K were examined. Both GB and SB showed properties similar to hydrated sodium silicate glass, to some extent. SB was more thermally stable than GB, but the spherical structures of both microballoons were collapsed by heating at 973 K; cristobalite was observed in samples heated at 973 K. The loosely and tightly incorporated water molecules evolved up to 573 K and near 850 K, respectively. The crystallization of cristobalite caused tightly incorporated water molecules to develop. The ultramicropores accessible only to H2O molecules in SB gradually decreased by heating and disappeared by heating at 773 K.

When a melt seeded with droplets of a volatile liquid is rapidly decompressed, the droplets explosively vaporize, taking their latent heat of vaporization from the melt and, therefore, homogeneously cooling and expanding it. The possibility of using this dynamic decompression and cooling (DDC) technique for producing an amorphous metallic foam is theoretically investigated. To test the premises of this theoretical model, preliminary experiments with an organic melt (p-terphenyl) seeded with water drops were performed. Results of these experiments demonstrate the potential of this novel approach to materials processing.

We are developing techniques to isolate and characterize grain boundary defects with controlled geometries in 1,6-di(N-carbazolyl)-2,4 hexadiyne (DCHD) diacetylene polymer bicrystals. To be successful in this endeavor, it is important to determine the influence of processing variables such as evaporation rate, solution concentration, and environment on DCHD diacetylene crystal morphology. We have found that large, high quality DCHD diacetylene single crystals can be grown from solution under a controlled atmosphere. The quality of the DCHD crystals can be evaluated by optical microscopy and quantitative digital image analysis. Defect structures in DCHD diacetylene crystals have been studied by transmission electron microscopy (TEM). Two single-crystal textured structures have been found in porous DCHD crystals precipitated from solution: (1) a microfibrillar structure and (2) a “cross-hatched” structure. The porous DCHD crystals show localized shear deformation zones (twins and kinks), but only in those regions where the density is greater than 95% that of the perfect crystal. Lateral chain invariant (LCI) small-angle grain boundaries have been identified in DCHD by HREM.

Ion irradiation with various oxygen flow rates has been carried out to improve the wettability of polymethylmethacrylate (PMMA) to water and to enhance the adhesion between Al and the polymer. Ar+ ion and oxygen ion were irradiated on the polymer, and amounts of ions were changed from 5 × 1014 Ar+/cm2 to 5 × 1016 Ar+/cm2 by a broad ion beam source. Oxygen gas from 0 ml/min to 7 ml/min was flowed near the polymer surface during the ion irradiation, and the energy of ions was changed from 500 eV to 1500 eV. The wetting angle was reduced from 68° to 49° with the Ar+ ion irradiation only at 1 keV energy, to 43° with the oxygen ion irradiation, and dropped to 8° with Ar+ ion irradiation with flowing 4 ml/min oxygen gas near the polymer surface. Changes of wetting angle with oxygen gas and Ar+ ion irradiation were explained by a two-step chemical reaction among polymer matrix, energetic ions, and oxygen gas. The effects of Ar+ ion and oxygen ion irradiation were explained by considering formation of hydrophilic groups due to a reaction between irradiated polymer chain by energetic ion irradiation and blown oxygen gas, and enhanced adhesion between Al and PMMA was explained by the formation of electron acceptor groups in polymer and electron donors in metal, and by the chemical reaction in the interface between irradiated polymer surface and deposited metal.