A novel thermomechanical processing technique for the synthesis of bulk submicron grain (grain size ≈200 nm) 304 stainless steel is reported. This ingot-metallurgical technique requires a total deformation of only 95%, and the key steps to this processing technique involve (i) formation of ultrafine dislocation cell structure, and (ii) the conversion of dislocation cells into grains with medium to high misorientation by grain boundary sliding.

The electrical resistivity property of RuO2 thin films grown on the SiO2/Si substrate by reactive dc sputtering was examined in terms of microstructure using x-ray diffraction and cross-sectional transmission electron microscopy. As the samples were annealed in the oxygen ambient over the temperature range 300–700 °C, the resistivity decreased from 270 to 90 μΩcm with increasing annealing temperature. When heat treatment was performed below 500 °C, the strain which accumulated in the RuO2 layer during deposition was released without significant increase in grain size. It is thought that below 500 °C improvement in the crystallinity plays an important role in the variation of the resistivity. Although a considerable amount of growth of RuO2 grains was achieved, the columnar structure of the RuO2 layer in the as-deposited sample remained unchanged even after annealing at 700 °C. The resistivity improvement above 500 °C was driven mainly by the grain boundary annihilation.

A new method is proposed to prepare bulk nanocrystalline alloys by quenching alloy melts under high pressure. Due to application of pressure to solidification processes, the nucleation rate is increased whereas the growth rate of nuclei decreased with increase of pressure, which makes it possible to obtain bulk ingots with nanometer-sized crystalline grains if appropriate pressure, temperature, and cooling rate are selected. The as-pressure-quenched products are cylinder-like with diameter about 4 mm and height several millimeters. This method can produce dense, free-porosity bulk nanocrystalline alloys with clean crystalline interfaces, promising use for experimental research and technological applications.

Iron nitride and iron carbonitride (ICN) ultrafine particles (20–80 nm in size) have been synthesized by laser-induced pyrolysis of the Fe(CO)5–NH3–C2H4 system. The oxidation behavior, surface morphologies, and structural characteristics as well as magnetic properties of these particles are reported and discussed. It is found that the presence of very thin carbon coating (1–2 nm) on the ICN particles plays an important role in preventing the oxidation of the particles. Accordingly, the ICN ultrafine particles exhibit higher saturation magnetization (142 emu/g) than the iron nitride ones (124 emu/g).

Bulk single crystals of Y123 are required to clarify the superconductivity phenomena and develop electronic devices using unique superconductive properties. Only the Solute-Rich Liquid–Crystal Pulling (SRL-CP) method has succeeded in continuous growth of the Y123 single crystal. In this paper, we investigated the growth of Y123 single crystals under different temperature gradients in the solution in order to understand the growth mechanism of Y123. It was revealed that Y123 single crystals grow with a spiral growth mode, which is in good agreement with the BCF theory.

Superconducting oxide films of YBa2Cu3O7−δ (YBCO) were produced on magnesia (MgO) single crystalline substrates (100) by laser-assisted metal-organic chemical vapor deposition. The highly volatile Ba(hfa)2 · tetraglyme was used as a Ba source metal-organic material. Smoother surface YBCO film was obtained with KrF laser irradiation than without. However, KrF laser irradiation does not lower the temperature for formation of YBCO(123) phase. YBCO film prepared at 750 °C on the MgO substrate showed a Tc(R = 0) of 69 K, and that prepared with KrF laser irradiation was 85 K. When water was added to the reaction chamber, barium fluoride was reduced and the YBCO formation was detected at a temperature of 650 °C and higher. YBCO film prepared at the temperature of 700 °C for 40 min without KrF laser irradiation behaves as a semiconductor, and one prepared with laser irradiation showed a Tc(R = 0) of 78 K.

This work deals with the influence of the starting Y-123 grain size on the growth mechanism and final microstructure of the melt-textured YBa2Cu3O7−x ceramics. Observations of the growth front morphology and stability for the different precursors using several decomposition temperatures are correlated with the theoretical equations. It is found that the final 211 inclusion size increases as the starting 123 grain size increases. However, using a small-grained 123 precursor disrupts the growth front and makes the control of grain alignment difficult. An appropriate morphology of the 123 precursor should be chosen prior to the MTG process in order to obtain the best properties.

This study investigates the influences of Y–Ba–Cu–O compounds solidification under different oxygen partial pressures by a zone melting method. In the Y–Ba–Cu–O system, P(O2) ranged from 0.02 to 1 atm, and the following reaction occurred during heating: YBa2Cu3O6−δ (Y123) → Y2BaCuO5 (Y211) + L. With an increase of oxygen partial pressure or decrease of pulling rate, the morphology of the solidified interface changed from mushy to equiaxed, cellular, and planar. The continuous Y123 grains were readily obtained under high oxygen partial pressure. Based on the constitutional supercooling theory and combining the result of the yttrium solubility limit for different oxygen partial pressures, the influences of oxygen partial pressure on Y123 morphological evolution were clarified.

A ferromagnetic and supersaturated fcc Fe60Cu40 solid solution was prepared by mechanical alloying (MA). The phase transformations of the as-milled Fe60Cu40 powder upon heating to 1400 °C and subsequently cooling to room temperature were characterized by differential thermal analysis (DTA) and thermal magnetic measurement. The fcc Fe60Cu40 solid solution decomposes into α–Fe(Cu) + γ–Fe(Cu) + Cu(Fe) upon heating from 300 to 460 °C, and on further heating, α–Fe(Cu) transforms to γ–Fe(Cu) at 640 → 760 °C; during cooling, the reverse transformation occurs from 800 → 640 °C (obtained from thermomagnetic measurement) or from 700 → 622 °C (obtained from DTA). The γ ⇆ α transformation in mechanically alloyed Fe60Cu40 nanocrystalline occurs in a wide temperature range; the transformation temperature is higher than that of the martensite transformation in as-cast Fe–Cu alloys, but is much lower than that of the allotropic transformation of pure Fe. These differences may be caused by the different fabrication process, the nonequilibrium microstructure of MA, as well as the inhomogeneous grain size in α–Fe(Cu). High resolution transmission electron microscope (HRTEM) observations carried out in the specimen after the DTA run show that N-W or K-S orientation relationships exist between α–Fe(Cu) and Cu(Fe), which also represent the orientation relationship between α–Fe(Cu) and γ–Fe(Cu) due to excellent coherency between γ–Fe(Cu) and Cu(Fe). The grain size of the α–Fe(Cu) is inhomogeneous and varies from 50–600 mm. Energy dispersive x-ray spectroscopy (EDXS) result shows that the Cu content in these α–Fe(Cu) grains reaches as high as 9.5 at. % even after DTA heating to 1400 °C, which is even higher than the maximum solubility of Cu in γ–Fe above 1094 °C. This may be caused by the small grain size of α–Fe(Cu).

An ultrahigh-carbon (1.25 wt.%) steel alloy containing 10 wt.% aluminum (UHCS–10Al) was processed by a powder metallurgy technique. Gas-atomized powders were subjected to ball-milling in an attritor in order to obtain a submicrometer grain size. Powder material was consolidated by both hot isostatic pressing (HIP) and by hot isopressure extrusion (HIE). Bulk material with submicrometer grain sizes was produced from attrited powders. The chemical composition and microstructure of this material are characterized at each processing step, from atomization through consolidation. Tensile tests show that a high strength results from the submicrometer grain size produced in the bulk material.

The hot deformation characteristics of a newly typed, high strength magnesium-based alloy, Mg–8.3 wt.% Al–8.1 wt.% Ga alloy, produced by rapidly solidified and powder metallurgy method have been investigated. Tensile tests were carried out at a temperature range from 523 to 623 K and a strain rate range from 10−4 to 1 s−1. Superplastic characteristics were found and, especially, a maximum elongation-to-failure of 1080% was obtained at 573 K and at a relatively high strain rate of 10−2 s−1. Because of the presence of fine microstructures at high temperatures, the optimum superplastic strain rate of the Mg–Al–Ga alloy was higher than that of the reported conventional superplastic aluminum and magnesium alloys.

The amorphous ternary metallic alloy Zr60Al15Ni25 was oxidized in dry oxygen in the temperature range 310 °C to 410 °C. Rutherford backscattering (RBS) and cross-sectional transmission electron microscopy (TEM) studies suggest that during this treatment an amorphous layer of zirconium-aluminum-oxide is formed at the surface. Nickel was depleted in the oxide and enriched in the amorphous alloy near the interface. The oxide layer thickness grows parabolically with annealing duration, with a transport constant of 2.8 × 10−5 m2/s × exp(−1.7 eV/kT). The oxidation rate may be controlled by the diffusion of Ni in the amorphous alloy. At later stages of the oxidation process, precipitates of nanocrystalline ZrO2 appear in the oxide near the interface. Finally, two intermetallic phases nucleate and grow simultaneously in the alloy, one at the interface and one within the alloy. An explanation involving preferential oxidation is proposed.

Polycrystalline diamond films were processed in a direct current plasma produced by a self-focused electron beam using combinations of H2, O2, and He as the processing gas. The film surfaces were observed by scanning electron microscopy, and characterized by x-ray photoelectron spectroscopy. It was found that for the case in which O2 was included in the processing gas, a high density of etch pits appeared on (100) faces of diamond grains, and oxygen was either physisorbed or chemisorbed at the film surface. It was demonstrated that the etching apparatus used was capable of forming at least a 5-μm wide pattern of polycrystalline diamond film.

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.

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.

A novel mosaic-like structure in SrTiO3 thin films was discovered and characterized by means of transmission electron microscopy (TEM). The films were deposited on a (001) oriented Pt surface. The orientation relationship between SrTiO3 film and Pt substrate was determined, and four types of growth modes were revealed. These four growth modes formed four types of domains, respectively, and these domains and Pt formed peculiarly ordered interfacial structures, i.e., near coincidence site lattices. Antiphase boundaries between two adjacent domains were also observed by high-resolution imaging.

Internal friction and torsional creep behaviors of high-purity single-crystal sapphire and three polycrystalline aluminas with different grain sizes have been measured up to very high temperature. The hexagonal c -axis-oriented sapphire specimen was tested at frequencies of 10–13 Hz, up to melting point (i.e., ∼2323 K). No relaxation peak was found and the exponential background curve was discussed in analogy to that of the hexagonal single-crystal ice reported in previous literature. The internal friction curves of the polycrystalline specimens were constituted by the superposition of a background component, of plastic nature, and a broad anelastic grain-boundary peak. These curves were markedly shifted to lower temperatures as compared to that of sapphire: the higher the shift, the smaller the average grain size. Also, the intensity of the grain-boundary peak decreased with increase in grain size. In the polycrystalline specimens, both creep and internal-friction background data fit the same Arrhenius plot, the slope corresponding to an activation energy of 200 kJ/mol. These data provide evidence for the occurrence of anelastic relaxation at the grain boundary and for the plastic nature of the internal-friction background in Al2O3 ceramics.

A new phenomenon in the field of Sialon ceramics is reported which may lead to applications based on their optical or electronic properties in combination with their mechanical and thermal properties. For the first time a colored α′-Sialon ceramic has been synthesized, with relatively high optical transparency by careful control of the sintering atmosphere, and adding suitable rare earths as stabilizing cations. This compares with normal Sialons and silicon nitrides which are grey-black in color and are opaque. Oxidation/reduction mechanisms have been identified as an influence on the valence of the stabilizing cation, which is responsible for the unusual optical properties.

Residual stress was measured in sintered and heat-treated Fe2TiO5 samples with various grain sizes. The influence of texturing was assessed by comparing the residual stress states of samples having randomly oriented grains and highly oriented grains produced through magnetically assisted processing. The residual stress was measured with x-ray diffraction using Cr Kα radiation. Due to the significant texture and the consequential oscillations in the dφψ vs sin2ψ data, the residual stress was calculated using the Marion–Cohen method. Textured samples showed significantly lower residual stresses except when spontaneous microcracking accompanied grain growth in the randomly oriented systems. Elastic modulus measurements showed a direct correlation between the decrease in residual stress and the microcrack density.

Particle packing techniques employing a liquid phase were used for preparation of dense disks of SiC and diamond particulates. Forty-one SiC and fifteen diamond compositions in the ternary-component particle systems were used to determine the optimum percentages of coarse, medium, and fine particles for achieving high packing densities: over 80% for SiC and over 62% for diamond. High packing densities were achieved without vibration by simply mixing the three size fractions in ethanol followed by stirring during the initial evaporation stage. The packing density results for SiC were successfully correlated with the percentages of the coarse and fine particles using multiple regression analysis; however, the data for diamond could not be similarly correlated with particle composition because the experimental work was done in a narrow range of compositions and the range of packing densities was small.