The ball-milling of pure Fe and Zn elemental powders corresponding to the Г-(Fe3Zn10), Г1-(Fe5Zn21), δ-(FeZn7), and ζ-(FeZn13) compositions yields metastable crystalline phases. This is demonstrated by the peaks observed in the DSC measurements of the different phases. These crystalline phases evolve differently with distinct or characteristic stages with heat treatments. Cold-welding and powder agglomeration are extensive, while the milled materials are completely homogeneous.

We report the electrical bistability of C60-tetracyanoquinodimethane (TCNQ) thin films fabricated by using an ionized-cluster-beam method in a high vacuum system. The films were characterized by transmission electron microscopy and electronic absorption spectroscopy. The spectroscopic results showed evidence of the formation of the charge-transfer complex system in C60-TCNQ thin films, and the TEM results revealed the microstructure of the films. The film thickness is ∼100 nm. The electromotive intensity at the transition point was of the order of 106 V/m. The possible mechanism of the electrical phenomena of the films is discussed in the paper.

Real and imaginary components of the impedance response on Co68.1Fe4.4B15Si12.5 amorphous as-cast wires were measured in the 100 Hz-100 kHz frequency range and 0.05–30 mA (RMS) current amplitude, at axial dc fields of 0 and 4800 A/m. From these data, plots of circumferential complex permeability as a function of circular field, as well as magnetization curves, were derived. Results are analyzed in terms equivalent circuits, which allows a resolution of domain wall and rotational contributions to the circumferential magnetization processes.

To reduce grain boundary weak links due to large-angle grain orientation mismatch, bulk (thick film) EuBa2Cu3O7−δ high-Tc superconductor specimens were biaxially aligned by a mechanical force such that their [001] axes were perpendicular to the specimen surfaces and by a magnetic force so as to orient their [010] axes to lie parallel to the magnetic field direction in the specimen plane. We describe here the characterization of such EuBa2Cu3O7−δ thick films by φ-circle XRD scans of (013) reflections, demonstrating a high degree (33%) of c-axis alignment with FWHM of <5° and approximately Gaussian distributions of a, b-axis alignment with a FWHM of 47°. The formation of “granular single crystals”, toward which this work is a further advance, can be seen as establishing a new paradigm in ceramics science.

A technique to accurately measure the formation enthalpies of transition metal compounds at relatively low temperatures using thick multilayer foils and differential scanning calorimetry is demonstrated. The enthalpy of formation of Cu51Zr14 was measured using 25 μm thick, free-standing Cu–Zr multilayer foils. The multilayers were deposited onto Si substrates using a planetary, magnetron source sputtering system. They were removed from their substrates, cut into 6 mm diameter specimens, and scanned in temperature from 50 °C to 725 °C in a differential scanning calorimeter. Three distinct exothermic reactions were systematically observed. The heats from the first two reactions were summed and then analyzed using a simple model that accounts for interfacial reactions and heat losses during deposition. The enthalpy of formation for Cu51Zr14 was measured to be 14.3 ± 0.3 kJ/mol. This quantity agrees with the single value of ΔHf = 14.07 ± 1.07 kJ/mol reported in the literature for this Cu–Zr compound. The advantages of measuring formation enthalpies using thick multilayer foils and low temperature calorimetry are discussed.

The effects of the addition of La2O3 (0.1 wt. %−1 wt. %) and MnO2 (0.1 wt. %−1 wt. %) on the piezoelectric properties of the 0.02Pb(Y2/3W1/3)O3−0.98Pb(Zr0.52Ti0.48)O3 system were investigated to develop the composition available for an actuator. In the case of the addition of La2O3 to the system, the maximum values of d33 and kp were observed in the 0.1 wt. % La2O3, and the values of Qm did not change with the amount of La2O3. The values of d33, kp, and Qm were 428 × 10−12 C/N, 57%, and 71, respectively. On the other hand, the introduction of 0.5 wt. % MnO2 as an acceptor into the system resulted in the maximum Qm value of 741, exhibiting a d33 of 298 × 10−12 C/N, and a kp of 50%. In the case of the simultaneous addition of La2O3 and MnO2, the best piezoelectric properties are obtained from the composition of 0.02Pb(Y2/3W1/3)O3−0.98Pb(Zr0.52Ti0.48)O3 + 0.1 wt. % La2O3 + 0.3 wt. % MnO2. The values of d33, kp, and Qm were 345 × 10−12 C/N, 55%, and 741, respectively.

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.

Compounds of the general formula M(SR)2 (M = Zn, Cd; R = i-Pr, t-Bu, Bz) have been prepared and explored as potential unimolecular starting materials for the preparation of binary group 12 metal sulfides. These new compounds have been characterized by IR spectroscopy and thermogravimetric analysis. Chemical derivatization of these insoluble metal-bis(thiolate) compounds by complexation with N-CH3 -imidazole renders them more soluble. These adducts were investigated by elemental analysis. Thermolytic decompositions of both the parent and derivatized compounds have been carried out both in the solid state and by heating a suspension of the appropriate metal-bis(thiolate) compound in an inert high boiling hydrocarbon medium. The thermolysis products have been studied by GC/MS (liquids) and x-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and particle size determination (solids).

We investigate the mechanical and microstructural properties of a diamond-like carbon coating (DLC) which is deposited by plasma enhanced chemical vapor deposition (PECVD) onto an alumina/aluminosilicate glass composite used for biomedical applications. Ball-on-ring tests yield a fracture strength that is essentially influenced by the surface topology/roughness. The surface topology of the coating is investigated by atomic force microscopy (AFM). Tribology tests and nanoindentation represent the wear resistance and hardness; these are properties that are mainly influenced by the microstructural properties of the DLC coating. This microstructure is investigated by transmission electron microscopy (TEM) and analyzed by parallel electron energy loss spectroscopy (PEELS). For the general applicability of the coated composite, the interfacial adhesion of the DLC coating on the comparably rough substrate (roughness amplitudes and wavelengths are in the micrometer range) is important. Therefore, we focus on TEM investigations that show the interface to be free of gaps and pores that we, together with a characteristic microstructure adjacent to the interface, relate to the excellent adhesion. The interlayer consists of a high density of SiC grains, part of them directly bound to the substrate, and part of them bound to other SiC grains. This interlayer is followed by an essentially different region of the coating as concerns the microstructure; this region consists of nanocrystalline diamond particles embedded in an amorphous carbon matrix. It is this heterogeneous microstructure to which we attribute (i) the good adhesion based upon the interface stabilizing SiC grains, and (ii) the high hardness and wear resistance based upon the diamond nanocrystals in the coating.

Lanthanum-modified lead zirconate titanate ceramics Pb1−3/2xLax(Zr1−yTiy)O3 [PLZT 100x/100(1 − y)/100y] with Zr/Ti ratios close to the antiferroelectric-ferroelectric (AFE-FE) phase boundary were investigated by dielectric spectroscopy, Sawyer–Tower polarization techniques, and electron microscopy. An incommensurate antiferroelectric (AFEIn) phase was found to be stabilized from the rhombohedral FE state in the compositional series 100x/90/10 for x ≥ 0.02. The La content required to induce the AFEIn state increased as the Ti content was increased. For 100x/85/15, a state with relaxor-like dielectric behavior and nanodomains was observed to develop with increasing La content; however, the double-loop-like P-E curves were suggestive of antiferroelectric behavior. Investigations for the composition 6/85/15 revealed the formation of nanodomains from the AFEIn modulation, where the size of the nanodomains equaled the value of the AFEIn modulation wavelength. For this composition, P-E studies revealed double hysteresis characteristics, whereas dielectric investigations revealed relaxor-like behavior. It is suggested that the order within the nanodomain state may be antipolar over a range of compositions in high La content rhombohedral PLZT ceramics.

The high strength medium temperature and β metastable titanium alloy, β-CEZ, is designed for use in the compressor of a jet engine. The purpose of this research was to investigate how the thermomechanical treatments (forging or solutioning conditions and quenching) influence the microstructure. A series of various heat-treating steps were conducted in order to quantify the relationship between thermomechanical parameters and microstructural factors. The detailed characterization of microstructure was based on SEM observations of primary alpha platelets with the aid of an Image Analysis system. A pronounced influence of thermomechanical treatments on microstructure was found. Several parameters characterizing the microstructure of alpha platelets such as the area fraction, length, width, perimeter, surface, density, and aspect ratio, have been found to depend on the solutioning conditions. Furthermore, with the exception of the area fraction, these different microstructural parameters were found to be also governed by the forging conditions.

The microstructural and microchemical changes produced in a Ti–25Al–10Nb–3V–1Mo alloy (at. %) by charging at high temperatures in high pressures of hydrogen gas have been studied using transmission electron microscopy (TEM) and x-ray methods. Hydrides incorporating all of the substitutional solutes that formed during charging have a face-centered cubic (fcc) structure and exhibit either a plate or fine-grained morphology. With increasing hydrogen content, the size of the hydrides decreases and their microchemistry changes as they approach the stable binary hydride, TiH2. Rejection of substitutional solute elements from the hydride produces changes in the microchemistry, and consequently in the crystal structure, of the surrounding matrix. In alloys containing 50 at. % H, this solute redistribution results in the formation of an orthohombic substitutional solid solution phase containing increased levels of Nb. The driving force of this redistribution of solutes is the reduction in the chemical potential of the system as the amount of the most stable hydride, TiH2, forms. The hydrides reverted to a solid solution on annealing in vacuum at 1073 K, and the original microchemistry of the alloy was restored. Reversion from the hydride structure to the original α2 ordered DO19 structure proceeds via a disordered HCP phase.

A discussion of the embrittlement of B-doped and B-free Ni3Al is given. Tensile test data and SEM fractography have been evaluated to show that additions of Pd to polycrystalline Ni3Al (B) essentially eliminate the embrittlement concomitant to charging Ni3Al (B) to the level of ∼5 wt. ppm of hydrogen.

The sintering behavior of 80SiO2–20TiO2 sol-gel thin films on Si wafers, prepared by spin coating, was studied by the calculation of density as a function of temperature, from refractive index measurements and the Lorenz–Lorentz relationship. The sintering kinetics of the films were fit to the Mackenzie and Shuttleworth model, over the temperature range of 700 °C–850 °C. Using this model, the viscosity was determined as a function of temperature. These gel films sintered to full density at 850 °C.

The tensile properties of the β-CEZ titanium alloy (Ti Al, 2Sn, 4Zr, 4Mo, 2Cr, 1Fe wt. %) have been investigated at intermediate temperatures as a function of the thermomechanical treatments. the strength and ductility have been correlated with the microstructural changes caused by the various heat treatments. It is found that the highest yield strength is associated with a structure containing a small area fraction, a small size, and a high density of primary α platelets (αp). Moreover, the size of the secondary α phase (αs) has been found to affect the yield strength. It is concluded that the ductility is enhanced by a high area fraction of αp platelets and is also sensitive to the density and the morphological orientation of the αp platelets. The interfaces between the αp and β phases play a dominant role in β-CEZ tensile behavior, and transgranular fracture is the main failure feature of this alloy.

The steady-state creep behavior of a particle-strengthened alloy of niobium (Nb–1Zr–0.1C) was compared with pure niobium and a Nb–1Zr alloy. The approach to a threshold stress was indicated at stress levels below 16 MPa and was supported by a statistical analysis of mean particle size. Analysis of the crept microstructure showed a classic dislocation substructure whose cell size was inversely proportional to the applied stress except at very low stresses. The smaller than predicted cell size observed at low applied stresses was attributed to the particles, preventing the dislocation cells from reaching their equilibrium dimension. Some amount of particle growth was observed which led to a reduction in creep resistance with time.

Blended elemental W–7 wt.%Ni–3 wt. %Fe powders were mechanically alloyed in a planetary ball mill and a heavy duty attritor. The structural and morphological characteristics of the as-milled powders were characterized by x-ray diffraction and electron microscopy techniques. A ternary solid solution of Fe and Ni in W formed in both the cases; the amount of Ni and Fe dissolved is higher in the attritor-milled powder than in the ball-milled powder. Morphologically, the W-rich particles in the attritor-milled powders were spheroidal, smaller in size, and showed a narrower size distribution than in the ball-milled condition. These differences led to increased density in the attritor-milled powder compact and significant differences in chemical composition of the matrix region and W-rich grains. Transmission electron microscopy investigations of the matrix region in the compacts revealed the presence of Fe2W precipitates uniformly distributed in an Ni(Fe, W) matrix.

Y1Ba2Cu307−x (Y123) crystals were grown by two different methods, the constant undercooling solidification and the continual cooling method, with top seeding by Sm123 seed crystals in order to investigate a relationship between undercooling (ΔT) and a growth rate (R). The crystals of Y123 with a sharp faceted interface, which consisted of {100} and {001} faces, grew epitaxially from the seed. It was found that the growth rates of {100} face (Ra) and that of {001} face (Rc) showed an increasing trend with increasing ΔT, and Rc was faster than Ra within these experimental conditions, ΔT < 20 K. The relation between R and ΔT follows the parabolic equation, viz. Ra ∝ ΔT1.9 and Rc ∝ ΔT1.3 for {100} and {001} faces, respectively. The simulated crystal size using the R and ΔT relations obtained from the constant undercooling method showed good agreement with experimental data by the continual cooling.

Studies of the reactions between rare earth salts and phosphoric acid in aqueous or ethanolic media have shown that in both cases stable gels can be formed. Upon drying, gels prepared in aqueous environments yield macrocrystalline REPO4 products similar to those produced by conventional precipitation and drying. Gels prepared in ethanol, on the other hand, undergo dehydration to form dense microcrystalline products. This observation is based on optical and scanning electron microscopy, as well as on x-ray diffraction studies and infrared spectroscopy. These techniques, as well as differential thermal analysis, indicate that crystal growth of these products takes place around 600−700 °C. The composition of the dehydrated gels produced in both the aqueous and ethanolic systems corresponds to an orthophosphate structure. Other characteristics of the microcrystalline REPO4 products include high resistance to attack by water, absence of coloration upon exposure to gamma rays, and a high index of refraction.

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.