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The carbide formation during the solid-state reaction between thin films and the solid-state reaction between 11 transition metals and an amorphous carbon layer are examined. In situ x-ray diffraction is used to obtain the activation energy for the formation of the various carbide phases.

Thermal characteristics of Nb2SnC, a ternary carbide, were studied.

Nanoscale friction was observed at the interface between a boron carbide film and an atomic force microscope tip.

Magnetic Fe3C and alpha-Fe ultrafine particles were produced by laser-induced pyrolysis of Fe(CO)5 and C2H4. It was seen that after passivation, the Fe3C particles had a high saturation magnetization of 132 emu/g compared to that of the alpha-Fe particle, 95 emu/g. It was also observed that the oxygen is in different states for the two ultrafine particles. The oxygen on the Fe3C particles was mainly in absorbed form, in contrast to the chemically combined oxygen in the alpha-Fe particles.

Ti carbide layers are synthesized by multipulse excimer laser (lambda = 308 nanometers) irradiation of Ti samples in ambient CH4 gas at superatmospheric pressure. Nonstoichiometric carbides with low carbon content are observed by the bulk of the samples. The laser fluence/number of pulses' combination is optimum. Large perturbation of the sample's surface is observed by an increase in the number of applied pulses. A model is proposed to explain the properties of the laser.

The development of n- and p-type capacitors on good quality SiC epitaxial layers facilitates routine capacitance and conductance measurements for large range of temperature. Conductance measurements applicable to metal-oxide-semiconductor, carried out in SiC epitaxial layers, indicate that trap time constant for good quality SiC epitaxial layers is equal to that of the Si-SiO2 interface.

Alloys deposited by radio frequency discharge correlates the composition microstructure and optical properties of a-Si(1-x)Cx:H thin films. The thin films have several stoichiometries and very small x-ray scattering angle. The alloys, subjected to ultraviolet, visible and infrared spectrometries, indicates the existence of microvoids between 3 to 8 angstroms.

A new study investigates the temperature behavior of the elastic properties of Ti3AlC2 and Ti4AIN3 in the range 90-300 K.

Appropriate melt-spinning techniques, depending on the concentration of carbon, help in the preparation of Tm2Fe17Cx compounds, where x is the C concentration. An increase in x increases lattice parameters and unit-cell volumes. Up to an x value of 1.5, there is an enhancement of spin-orientation temperature, beyond which this temperature decreases. Higher concentrations of C do not affect the Tm sublattice anisotropy. X-ray diffraction studies reveal these compounds to be single phase.

Melt spinning is used to synthesize (Er(sub 1-x)Sm(sub x))(sub 2)Fe(sub 17)C(sub y) carbide complexes with a carbon concentration of 30% in the Er region and 15% in the Sm region. The complexes crystallize in a hexagonal Th(sub 2)Ni(sub 17)-type and a rhombohedral Th(sub 2)Zn(sub 17)-type structure. (Er(sub 1-x)Sm(sub x))(sub 2)Fe(sub 17)C(sub y) is stable at a very high temperature. Curie temperatures and unit-cell volumes of the complex are enhanced by saturation magnetization of the complex.

The hard magnetic characteristics of melt-spun Nd(Fe,M)12 nitrides and carbides were investigated. The results showed that maximum coercivity was attained for a 4-hour nitrogenation at 570 dgrees celsius. The purity of the ThMn12 phase and the purity of nitrogenation/carbonation significantly influenced the resulting hard magnetic properties of the material.

The characteristics of mechanically alloyed NdFeMoN nitrides and NdFeMoC carbides were investigated. The results showed that when the Mo content was reduced, both the Curie temperature and magnetization saturation increased. In addition, the coercivity of the lower Mo content NdFeMoN decreased. This was offset by the addition of Dy. The nitride and the carbide samples exhibited the same behavior although the former had a much lower coercivity.

The development of coercivity in Sm2Fe17(N,C)x magnets by mechanical alloying, solid-gas reaction and pressure-assisted zinc bonding was reported. Vacuum heat treatments at 700 to 800 degrees celsius was used to form microcrystalline Sm2Fe17 from mechanically-alloyed, highly coercive Sm2Fe17Nx powders. A solid gas reaction in N2 and C2H2 atmosphere at temperatures ranging from 400 to 500 degrees celsius introduced nitrogen and carbon into the interstitial sites.

The characteristics of high carbon concentration in Gd2Fe17Cx prepared by melt quenching were investigated using Mossbauer spectroscopy. The results showed that the average hyperfine field and isomer shift increased as the carbon concentration was increased. This increase was observed to be slower when x was greater than 1.0 but faster when x was greater than 0.5. This behavior was attributed to volume effects and band structure variations.

The magnetic characteristics of highly stable (Er0.9Y0.2)2Fe17Cx carbides prepared by arc melting and melt spinning were investigated. The results showed that the sample had a single phase hexagonal structure. When x=1.5, the samples transformed to the Th2Zn17 structure. When x was greater than 1.5, only optimal samples crystallized in the structure. Carbide samples with x=2.8 featured a 6.5% volume expansion.

The deviatoric response of the dense ceramic, tungsten carbide is investigated under shock loading conditions, using laterally mounted stress gauges. The results indicate that lateral stress increases, and thus shear strength decreases behind the shock front.

The study of the temperature behavior of Ti/TiC system addresses several peculiar diffusion-related effects on carbides. The study is focused on the interface reaction and the microstructural evolution in the Ti/TiC multilayer using transmission electron microscopy, x-ray diffractometry, Auger electron spectroscopy, and differential thermal analysis as investigating tools.

A series of plate impact experiments that included reshock and release configurations were conducted in order to understand the behavior of boron carbide towards dynamic compression, dynamic strength and phase transformations. A complete set of data on the behavior of boron carbide is available but further studies are needed to evaluate the process of loss and retention of strength in boron carbide.

A classical potential for ZrC is developed in the form of a modified second-moment approximation with emphasis on the strong directional dependence of the C - Zr interactions. It is suggested that the present description could well serve as an appropriate template for other metallic ceramics, such as TiC and HfC.

A study was conducted, by using scanning tunneling microscopy and x-ray absorption near-edge spectroscopy, to examine the spontaneous formation of titanium carbide nanoislands on silicon carbide substrates. The result found uniformly distributed islands at the lowest coverage, and the islands tend to collect at the substrate step edges at higher coverage.

A study was conducted on the unusual combination of properties exhibited by the layered, hexagonal ternary carbide Ti3SiC2. The experiment investigated the low temperature heat capacity of Ti3SiC2 using a standard adiabatic calorimeter in a liquid helium cryostat to perform calorimetric measurements in the two to 10 K temperature range. The study provides additional insights to the unusual behavior of Ti3SiC2 in terms of a large Debye temperature and a sizable but somewhat reduced density of states at the Fermi level in comparison with that of pure Ti.

The relative stabilities of the four stoichiometric and substoichiometric MoC phases, the eta and gamma(TiAs) phases, the cubic delta(NaCl) phase and the three hexagonal gamma(WC) were analyzed by using total energy methods. Results show that the trends in relative stabilities are exhibited when introducing vacancies in the carbon sublattice. However, the order of stability between the phases is altered when switching from stoichiometric to substoichiometric MoC.

The response of the ceramic, boron carbide (B4C) to severe loading conditions that induce large strains, high strain rates and high pressures was investigated. Experimental data from previous studies were employed to determine and/or estimate constants for the JH-2 constitutive model for brittle materials. Several Lagrangian finite element and Eulerian finite difference calculations were performed to demonstrate responses for several impact and penetration problems.