An intermetallic Fe3Al alloy was cast, hot rolled, annealed (870 K), and finally quenched. After this treatment, the alloy had an imperfectly ordered B2 structure. The polycrystalline sample was then warm rolled at 800–830 K. The crystallographic texture of the rolled specimen was quantitatively studied within the range, ∈ = 20–80%. Even at large strains (∈ = 80%), recrystallization was not observed in the microstructure. It was found that the rolling texture of Fe3 Al is very inhomogeneous through the sample thickness. In the center layer, a large volume fraction of grains with a {111} lattice plane parallel to the sheet surface, {111}〈uvw〉, and a weak {001} 〈110〉 component were observed. In contrast, close to the sheet surface layer, a weak texture containing the {11 11 8} 〈4 4 11〉 and the {012} 〈110〉 orientations was formed. The results are interpreted in terms of the activation of {110} 〈111〉 and {112} 〈111〉 slip systems. The through-thickness texture gradient was attributed to the inhomogeneous strain distribution during rolling, leading to plane strain in the center layer and to shear strains close to the surface.

The debinding process of injection-molded compacts of Fe–8Ni mixed powders, containing binders of different ratios of polymers to wax, was investigated. The effect of binder compositions and debinding conditions on the sinterability of the compacts were also studied. Distortions produced in the debinding processes of the compacts were minimized for the case where a ratio of polymer to the total binder contents was 0.35. In the case of the compacts debound in air, sintered densities increased by increasing the debinding temperature up to 350 °C, then decreased sharply for higher debinding temperatures. In the compacts debound in N2, sintered densities were almost independent of the debinding temperature. The sinterability of the compacts debound in N2 was inferior to that debound in air.

The dielectric constants (K) have been measured near ambient temperature for polycrystalline bulk ceramics of the crystallographic shear compounds TiNb24O62, Ti2Nb10O29, and TiNb2O7. These show enhanced K's over Nb2O5 and TiO2, with the 2: 10:29 phase displaying an ambient temperature K of approximately 130. We also report the effects of partial substitution of Nb by Ta. In general, the dielectric constants are enhanced for 5–10% Ta substitution, with the detailed behavior differing for the three phases.

A rapidly solidified alumina-zirconia eutectic material containing nanocrystalline t-ZrO2 has been synthesized. When heated, the microstructure contained a mixture of t-ZrO2 and m-ZrO2, each of which can facilitate toughening of the composite. Dynamic shock compaction was used to accelerate densification of the material, producing crack-free specimens with high green densities. After sintering to densities measuring ∼95% of theoretical, the shock-compacted specimens fabricated with unstabilized alumina-zirconia were extensively microcracked due to an overabundance of the m-ZrO2 phase. Experiments employing Y2O3 as a chemical stabilizer have shown that the extent of the phase transformation can be controlled, and the microstructure that developed in the stabilized material contained an acceptable level of the microcrack generating m-ZrO2 phase.

Compressive creep behavior of fine-grained (5 μm) La0.9Sr0.1MnO3 with a relative theoretical density between 85 and 90% was investigated over the temperature range 1150–1300 °C in air. The fine grain size, brief creep transients, stress exponent close to unity, and absence of deformation-induced dislocations, suggested that the deformation was controlled by a diffusional creep mechanism. The activation energy for creep of La0.9Sr0.1MnO3 was 490 kJ/mole. A comparison of the activation energy for creep of La0.9Sr0.1MnO3 with existing diffusion and creep data for perovskite oxides suggested that the diffusional creep of La0.9Sr0.1MnO3 was controlled by lattice diffusion of the cations, either lanthanum or manganese.

The frictional behaviors of fullerenes C60 and C70 were studied because they were speculated to be solid lubricants. For the sublimated pure C60 films on Si(001), a high friction coefficient (0.55–0.8) was observed under different loads and pin materials. For the C70 film, the friction coefficient showed a pin dependence, which changed from 0.5 with an Al2O3 pin to about 0.9 with a 440 stainless steel pin. The relatively high friction coefficients of C60 and C70 films were due to the tendency of the C60 and C70 particles to clump and compress into high shear strength layers rather than due to the impurities in the fullerenes. The benzene-solvated C60 · 4C6H6 and C70 ·xC6H6 showed a lowered friction coefficient (0.25 for C60 · 4C6H6 and 0.3 for C70 · xC6H6), which might result from the lowered shear strength of the hcp structure of C60 · 4C6H6 and C70 ·xC6H6 molecular crystals in which the benzene molecules were intercalated.

Electronic structure calculations were carried out for bcc iron grain boundaries (GB) with or without hydrogen, using the self-consistent Discrete Variational embedded cluster method within the first-principles local density formalism. Bonding characteristics were mainly investigated. Simple rigid body translations perpendicular to the GB plane were used for estimation of relaxed GB geometry. Analysis of bond order summation over the GB shows considerable volume expansion normal to the GB plane of a dense 23(111) twist/tilt GB and some compression for the rather open 23(110) twist configuration. These results are discussed in the context of atomistic simulations which suggest that higher energy GB's generally have larger volume expansion normal to the GB plane. H in a 23(111) GB reduces Fe-Fe bonding strength by —3% within a 0.25 nm spherical volume around the H site, associated with reduction of the 4s and 4p occupancy of the nearest neighbor Fe. Since these orbitals contribute mainly to metallic bonding, the action of H atoms as an embrittlement inducer can be understood.

We studied composition, structure, microstructure, and magnetic properties of percolating (Ni–Fe)x(SiO2)1−x granular thin films. We found that the magnetic susceptibility increases and the coercivity decreases when increasing x toward xt, the critical metallic volume fraction for the metal-insulator transition, and the susceptibility decreases and the coercivity increases when increasing annealing temperature for x just below xt. Comparison of the microstructure and the magnetic properties suggests that the enhanced magnetic susceptibility for x just below xt is probably associated with the labyrinthine structure of the granular magnetic particles where there is an enhanced surface-to-volume ratio of the magnetic particles.

Sintering, glass crystallization, microstructure, and the resulting properties of spodumene-borosilicate glass composites were investigated. Densities >90% could be obtained for samples sintered below 1000 °C. Samples that contained more low-viscosity glass densified at lower temperatures, and significant density reduction was observed at higher temperatures. Samples that contained high-viscosity glass densified only at higher temperatures. When glasses of different viscosity were added, the densification of the composites was improved. There was interdiffusion between spodumene and glass. Cristobalite crystallized from the pure glasses. Addition of spodumene changed the major phase crystallized to anorthite or α-quartz as a result of dissolution of spodumene into glass. Composites that contained glass of higher silica content showed more crystallization. As sintering temperatures increased, the amount of crystallization decreased, due to dissolution of glass into spodumene. The spodumene particles showed angular shape with smooth and straight sides. The spodumene-glass composites showed a dielectric constant in the range of 5–6, a loss tangent generally <1%, and a CTE value in the range of 2–5.6 × 10–6 K–1. Codoping of glasses with different viscosity effectively improved the densification and properties of the composites.

X-ray diffraction and temperature dependent (5 K–380 K) magnetic measurements have been carried out in INCONEL 718 superalloy before and after high temperature aging treatments. (INCONEL is a trademark of the INCO family of companies.) The nominal composition of this alloy is Ni (52.5%), Cr (19.0%), Fe (18.5%), Nb (5.1%), Mo (3.0%), Ti (0.9%), Al (0.5%), Cu (0.15%), and C (0.08%), and it yields an x-ray diffraction pattern consisting of a fcc phase with α = 3.5987 (3) Å and an orthorhombic phase associated with δ-Ni3Nb. It is concluded that the fcc pattern is due to both the γ austenitic phase and γ′ Ni3(Al, Ti) phase of alloy 718. The standard annealing and aging treatment carried out in air at temperatures between 621 and 982 °C produces surface oxides (Cr, Fe)2O3 and FeNbO4 (which are easily removed by etching and polishing) and contracts the lattice. Magnetic measurements show a distinct phase transition at Tc = 14 K, which has been attributed to the γ′-Ni3(Al, Ti) phase by the process of elimination and by observing that it has most of the characteristics of the weak itinerant ferromagnet Ni74.5Al25.5. This transition may have some effects on the cryogenic applications of this alloy.

The structure of a stable decagonal quasicrystal with 0.4 nm periodicity, formed in a conventionally solidified alloy with composition Al71.6Ni23.7Fe4.7, was investigated by high-resolution electron microscopy. It was found that this decagonal phase is one of the best-ordered quasicrystals, without any detectable linear phason strain and with only weak random phason strain. The structure is interpreted as an aperiodic tiling of decagonal atom columns with a diameter of about 1.2 nm. The atomic arrangements in special local regions are discussed on the basis of computer simulations.

Ferroelasticity of the tetragonal displacive (t′) phase was studied on 4.7 mol% Y2O3 partially stabilized zirconia single crystals. Samples were deformed at 1400 °C at constant strain rate to induce the ferroelastic behavior. Domain reorientation due to the applied stress has been studied as a function of the compression axis and aging time at 1600 °C. Domain switching was found in the as-received and 2-h-aged crystals deformed along the 〈100〉 direction, in which an exceptional high flow stress was reached (>700 MPa). Transmission electron microscopy observations were performed on deformed and undeformed crystals to study the microstructural changes associated with the domain switching. Incremental strain steps on the stress-strain curves and surface texture on the lateral faces of the deformed samples were correlated with the microstructural evidence.

Compressive creep deformation of hot-pressed silicon nitride with different amounts of grain boundary glassy phase was investigated at 1300–1400 °C under 30–100 MPa. The stress exponent of the creep rate was determined to be nearly unity. The apparent activation energy of silicon nitride with a larger amount of glassy phase was measured to be about 700 kJ/mole, and that with a smaller amount of glassy phase was found to be 400 kJ/mole. In addition, the microstructural observation found that no cavity appeared and grain boundary glass was recrystallized during creep test. Thus, the rate-limiting steps in solution/precipitation creep mechanism change from the solution-reprecipitation of Si3N4 grains to the diffusion through the grain boundary with increasing the amount of glassy phase.

Cubic (δ) bismuth oxide (Bi2O3) has been subjected to high temperature deformation over a wide range of temperatures and strain rates. Results indicate that bismuth oxide is essentially incapable of plastic deformation at temperatures below the monoclithic to cubic phase transformation which occurs at approximately 730 °C. Above the transformation temperature, however, Bi2O3 is extensively deformable. The variability of flow stress to temperature and strain rate has been quantified through the determination of phenomenological-based constitutive equations to describe its behavior at these high temperatures. Analysis of the so-determined deformation constants indicate an extremely strong sensitivity to strain rate and temperature, with values of the strain-rate sensitivity approaching values commonly cited as indicative of superplastic behavior.

Surface microroughness of various Si(100) wafers was detected and characterized by a 180° backscattering Rayleigh–Brillouin scattering spectrometer (RBSS), and measured by an atomic force microscopy (AFM). The intensity of the scattered light from the wafers is found to increase with increasing surface microroughness which was measured by AFM. By scanning across the wafer, the inhomogeneous distribution of surface microroughness is detected and characterized. The system can be easily developed into a mapping technique. The results of the surface microroughness detected by AFM and RBSS suggest that they are complementary for the characterization of the surface microroughness from a microarea to a whole wafer.

Ceramic (Ca1−xSrx)2PbO4 samples have been prepared with x = 0.00, 0.25, 0.50, 0.75, and 1.00 in order to study the change in lattice constants with the ratio of Ca/Sr. This phase is frequently an intermediate phase in the fabrication of Bi–Sr–Ca–Cu–O superconductors, and it is important to connect the lattice constants with stoichiometry. The behavior of the lattice constants closely follows Vegard's law.

We have designed tungsten carbide tools with a new binder, which makes them suitable for advanced diamond tool coatings. The new tool substrates, made of tungsten carbide and nickel aluminide as binder phase, are produced by sintering and hot isostatic pressing, and also by combustion synthesis. The high temperature strength of nickel aluminide is key to superior tool performance at elevated temperatures. More importantly, nickel aluminides reduce the formation of graphite and promote diamond growth during chemical vapor deposition. Diamond films are deposited on the new tool substrates to investigate the nucleation density, adhesion, and wear resistance. The diamond coatings are characterized by scanning electron microscopy and Raman spectroscopy. The graphitizing tendency due to cobalt in the tungsten carbide tools was found to be a limitation to improve adhesion of diamond films. The new tool substrates with nickel aluminide binder have been found to exhibit good adhesion and wear resistance. The implications of these results in advanced cutting tools are discussed.

To avoid the formation of hollow spheres during spray pyrolysis, NH3 was employed to change the mechanism of forming NiFe2O4 from aerosols, containing Ni(II) and Fe(III) nitrates in the required stoichiometric ratio. Nearly spherical, solid submicron NiFe2O4 particles with narrow size distribution were produced in one step using a dilute aqueous solution at pyrolysis temperatures as low as 823 K. However, higher pyrolysis temperatures (≥1023 K) reduced the oxides to metallic alloy of Ni and Fe due to dissociation of NH3. The forming steps and possible reaction mechanisms for aerosol droplets involved in the process were discussed.

Excellent quality boron nitride (BN) thin films on silicon have been produced by a simple procedure involving spincoating solutions of the “single-source” polymeric-precursor polyborazylene, (B3N3H∼4)x, on a silicon substrate, followed by pyrolysis at 900 °C. Rutherford backscattering spectrometry (RBS) indicates that the B/N ratios are 1.37 and 1.09 for conversions carried out in a vacuum oven at 900 and 1250 °C, respectively. Forward recoil spectrometry (FRES) showed that the atomic percent of residual hydrogen is 10 and 9%, respectively. Plain-view and cross-sectional scanning electron microscopy (SEM) studies showed that the samples annealed at 900 °C were clean and uniform in thickness. A thickness of 800 × 1015 atoms/cm2 was determined by ion scattering. Films annealed to 1250 °C likewise showed a continuous unbroken boron nitride layer, but also exhibited morphological features resulting from reactions of the underlying silicon oxide-silicon interface in the substrate. Auger electron spectroscopy and atomic force microscopy showed that the BN coating produced at this higher temperature remained unbroken but had a surface area of ∼15% covered by dimples 2–7 nm in depth. Compared to typical films made by chemical vapor deposition, BN films produced from this “single-source” method have lower hydrogen and carbon concentrations.

Using tabulated thermodynamic data, a comprehensive investigation of the thermo-dynamic stability of binary oxides in contact with silicon at 1000 K was conducted. Reactions between silicon and each binary oxide at 1000 K, including those involving ternary phases, were considered. Sufficient data exist to conclude that all binary oxides except the following are thermodynamically unstable in contact with silicon at 1000 K: Li2O, most of the alkaline earth oxides (BeO, MgO, CaO, and SrO), the column IIIB oxides (Sc2O3, Y2O3, and Re2O3, where Re is a rare earth), ThO2, UO2, ZrO2, HfO2, and Al2O3. Of these remaining oxides, sufficient data exist to conclude that BeO, MgO, and ZrO2 are thermodynamically stable in contact with silicon at 1000 K. Our results are consistent with reported investigations of silicon/binary oxide interfaces and identify candidate materials for future investigations.