We have used x-ray diffraction to characterize diamond films grown in three characteristic morphologies by chemical vapor deposition. Each morphology has a fiber texture about the growth direction; we report the crystal axis aligned in this direction for each morphology. In all cases the average lattice constant agrees with that of bulk diamond; we report the range of strain in each sample.

Scanning and isothermal calorimetry, together with x-ray diffraction and high resolution transmission electron microscopy (TEM), have been used to characterize Al–Mn and Al–Mn–Si films sputtered onto substrates at 60 °C, 45 °C, and −100 °C. In the case of Al0.83Mn0.17, the monotonically decreasing isothermal calorimetric signal, characteristic of a grain growth process, has proved decisive in identifying the as-sputtered “amorphous” state as microquasicrystalline, with an average grain size of ∼ 20 Å, in agreement with an estimate of correlation range from the x-ray pattern. The TEM at 400 keV reveals well-defined atomic or lattice images in annealed films but only barely resolved grains (ordered clusters) in the as-sputtered films. The relation between the metallic glass and the microquasicrystalline state in these alloys is discussed.

The ternary alloy Mg2Ni0.75Pd0.25 was made by the Replacement-Diffusion Method (RDM). Using x-ray analysis, scanning electron microscopy, AES analysis, and the BET method, the authors were able to characterize the structure of the alloy and study its surface properties. It has been found that the alloy thus obtained has excellent surface properties compared to that prepared metallurgically.

Cryomilling (high intensity mechanical ball milling in a liquid nitrogen bath) of the B2 crystal structure nickel aluminide leads to a NiAl composite containing about 10 vol.% of AlN particles. This is the result of a reaction milling process, where nitrogen incorporated into the matrix during cryomilling reacts with Al during subsequent thermomechanical processing to form the composite. Compressive testing at 1300 K of such materials densified by 1505 K extrusion or isostatic pressing at 1323 K or 1623 K indicated that strength at relatively fast strain rates (>10−7 s−1) is slightly dependent on the method of consolidation. At slower rates, however, no clear dependency on densification technique appears to exist, and four different consolidation methods possessed similar creep strengths. In all cases deformation at 1300 K occurred by two distinct mechanisms: at high strain rates the stress exponent is greater than 11 while at slower rates (<10−7 s−1) a much lower stress exponent (∼6) was found. Comparison of density compensated creep strengths reveals that the properties of NiAl–AlN are similar to those of the single crystal Ni-base superalloy NASAIR 100.

An x-ray powder diffraction method was used to determine the location of tantalum atoms in Ni3Al. A series of Ni3(Al, Ta) alloys were produced with tantalum contents ranging from 0.1 to 3.0 at.%. Fine powders with average particle sizes less than 80 μm were made from melt-spun ribbons by a grinding process. The values of the intensity of the (100) superlattice peak normalized to that of the (200) fundamental peak as a function of tantalum content agreed with the calculated values, assuming that tantalum atoms substitute on aluminum sites, not on nickel sites, and also assuming small amounts of anti-site defects exist in the ordered fee structure of Ni3(Al, Ta) alloys. It is concluded from our experiments that tantalum atoms substitute for aluminum in Ni3Al. The long-range order parameters thus calculated of the Ni3(Al, Ta) alloys are generally above 0.84 and below 0.95, except for Ni75Al24.8Ta0.2, at which composition the long-range order parameter is close to unity.

The nucleation and morphology of diamond crystals and films synthesized by the use of a combustion flame have been investigated. By operating an oxy-acetylene torch in a fuel-rich mode, diamond crystals and films have been deposited on mechanically abraded molybdenum, on in situ created molybdenum carbide, and on thin diamond-like carbon (DLC) layers synthesized on molybdenum. Scanning electron microscopy, Auger and Raman spectroscopy have been used to characterize the films and crystals. Diamond is found to be uniformly deposited in the region of the substrate that intersects the inner, acetylene-rich region of the flame. The nucleation density, the growth rate, and the morphology of the diamond crystals and films are found to be strongly influenced by the surface condition of the substrate. On mechanically abraded molybdenum, abraded with 600 mesh silicon carbide, and on molybdenum carbide, well-formed cubo-octahedrons of diamond, up to 45 μm in diameter, are formed for deposition times of 90 min. Film formation is seldom observed under these conditions. To enhance nucleation, thin layers of DLC were formed on molybdenum substrates by reducing the O2/C2H2 ratio in the gas mix to ∼ 0.75 for short periods of time under 30 s. This was followed by increasing the O2/C2H2 ratio to conditions that produce diamond (an O2/C2H2 ratio of ∼ 0.9). Under these conditions the nucleation density of diamond was increased by an order of magnitude and the growth rates by about 60%, as compared to diamond deposited on abraded molybdenum and molybdenum carbide. In addition, the morphology of the diamond crystals and films was substantially affected with indications of dendritic growth. The DLC layer is effective in promoting diamond nucleation due to the high surface defect density and the high hydrogen concentration of these films. The combination of surface defects, in the form of dangling bonds, and the evolution of hydrogen from the DLC layer during the diamond deposition process, which is characterized by higher temperatures, result in a high concentration of active surface sites for diamond nucleation. The nucleation density, the distribution on the substrate, and the morphology of diamond crystals and films are not driven by the transport of reactive specie in the flame to the substrate, but rather by nucleation processes, temperature distribution across the surface, and attendant surface phenomena.

Although amorphous alloys are known to be good diffusion barriers, amorphous nickel-zirconium is shown to react with Si at relatively low temperatures. Diffusion of Ni at 350°C through an amorphous Ni–Zr buffer layer leads to the formation of epitaxial NiSi2 on single crystal silicon substrates. Interplay of mobility and thermodynamics is applicable for epitaxial silicide nucleation and growth. Also, a one-step annealing process in oxygen ambient leads to bilayer formation of NiSi2/ZrO2 structures on silicon substrates.

The reaction of SiH4/H2 mixtures with iron and steels was studied at a total pressure of 1 atm and temperatures above 500 °C. When the amount of water vapor in the gas mixture is carefully controlled, a metal silicide diffusion coating forms at low temperatures (below 900°C). Composition and structure of the Si diffusion coatings were determined with Auger depth profiling and x-ray diffraction. Kinetics of the surface reaction between SiH4, and the metal substrate as well as the behavior of these films in severe environments at high temperatures were studied by a microgravimetric technique. Characterization of these Si coatings on iron, low carbon steel (1010), 9% Cr/1% Mo steel (alloy A182F9), and stainless steels (310) and their applications to reduce oxidation, nitriding, or coking at high temperatures or corrosion in mineral acids are described.

The solid solubility of magnesium in titanium under equilibrium conditions is reported to be extremely small. Mechanical alloying of a mixture of titanium and magnesium powders resulted in the formation of nanocrystalline (10–15 nm in size) grains of Ti–Mg solid solution. This solid solution has a metastable fcc structure with a = 0.426 nm and contains about 3 wt.% (6 at.%) magnesium in it. It is suggested that the fcc structure has formed as a result of the heavy mechanical deformation of the hep structure introduced during milling. High temperature annealing of the metastable solid solution led to its decomposition forming the equilibrium phases, viz., elemental titanium and magnesium.

The nucleation and growth kinetics of NiSi2 precipitation in amorphous silicon thin films ion implanted with nickel was investigated using scanning transmission electron microscopy. It was found that the nucleation rate could be approximately described by a delta function at time t = 0 when the films were annealed between 325 and 400 °C. The growth kinetics of the precipitates at these temperatures were described by r ∝ tn, where r was the average radius and n was about 1/3. This behavior is consistent with models for growth of three-dimensional particles in a two-dimensional diffusion field. It was also found that the implanted amorphous films displayed an enhanced rate of single crystal silicon formation, apparently catalyzed by migrating silicide precipitates.

The thermal analyses of iron nitrate in stagnant and flowing air using different heating rates were conducted to establish the intermediate phases and reactions during its decomposition. In view of the thermal results, the degree of pyrolysis of the aerosol formed by atomizing ferric nitrate aqueous solution was studied. Hollow spherical particles were obtained and varied from noncrystalline to crystalline materials, depending on the pyrolysis temperature used. The decomposition efficiency of resulting particles increased with the pyrolysis temperature.

Under circumstances in Zone-Melt-Recrystallization (ZMR) of Si-on-Insulator (SOI) structures where radiative heat loss is significant, the ∼50% decrease in emissivity when Si melts destabilizes the Si molten zone. We have demonstrated this both experimentally using a slowly scanned e-beam line source and numerically with a finite-element computational simulation. The resulting instability narrows the process window and tightens requirements on beam control and background heating uniformity, both for e-beam ZMR systems and optically-coupled systems such as a graphite strip heater.

Fine Ni particles were directly prepared from Ni(NO3)2 and NiCl2 aqueous solutions by the spray-pyrolysis technique under an H2-N2 atmosphere. Hollow Ni particles with rough surfaces were obtained at a low reaction temperature (700–900 °C). With increasing reaction temperatures from 900 °C to 1500 °C, the particles varied gradually to solid ones with a smooth surface, and the particles obtained at 1600 °C were perfectly spherical ones whose average size was ∼0.6 μm. From the point of view that aggregation free powders are considered to be good for thick film applications, Ni(NO3)2 was preferred to NiCl2 as a starting material. The perfectly spherical particles derived from Ni(NO3)2 gave a Ni film about 3 μm in thickness having sheet resistance of 37.7 mΩ · square−1.

Implantation of Al into nickel and co-evaporation of Ni–Al films onto nickel substrates followed by ion irradiation was conducted in order to investigate the mechanical properties of ion beam surface modifications and their relation to the composition and microstructure of the surface. Implantations were made using 400 keV Al+ to doses from 1 × 1015 to 6 × 1017 cm−2 at room temperature. Nickel films with 0–25% Al were co-evaporated onto nickel substrates and mixed using the same irradiation conditions but to a lower maximum dose. Hardness was measured using ultra-low load indentation, and residual stress was measured by the bending beam method. Results indicate that the primary contributor to the hardness increase of as-implanted surfaces is the irradiation-induced defects. The effect of Al in solution (γ phase) or Al in γ′ (Ni3Al) in either implanted or co-evaporated and mixed surfaces is evident only upon thermal treating to remove radiation damage. The high inherent hardness of the co-evaporated films is due to the small grain size of the film. The magnitude of the hardness in Al implanted nickel is very sensitive to the surface condition of the substrate. The observed hardness effects are all directly relatable to microstructure or phases present. Residual stresses change from tensile to compressive as a result of damage from low dose irradiation and heat treatment.

The changes in the chemistry and morphology within the interphase region of an SCS6/Ti–6A1–4V metal matrix composite upon exposing the samples to varying heat treatments have been studied using Auger electron spectroscopy, TEM and convergent beam diffraction techniques. These changes, such as the formation of small TiC particles at one interface and the narrowing of a protective pyrocarbon layer at another, induce fracture to occur at different places within the interphase upon heating. The reasons for this are explained. Evidence for a change in phase of a TixSiy(C) layer to the more thermodynamically stable Ti5Si3 is also given.

In this paper two methods for measuring aluminum compositions in very thin (1.5–15 nm), individual AlxGa1–xAs layers are investigated. The transmission electron microscopy (TEM) thickness-fringe method uses the bright-field extinction fringes from a small, cleaved 90° wedge imaged in a [100] orientation. By comparing calculated and experimental extinction fringes, compositions are determined with a sensitivity in x of 0.03, in layers with a thickness of 3.5 nm. With secondary ion mass spectrometry (SIMS), compositions in AlxGa1–xAs layers with a thickness of 15 nm are measured with an accuracy in x between 0.02 and 0.05. Thicker layers (1 μm) with a composition known from x-ray diffraction measurements are used as a reference for both methods. Subsequently, TEM results are compared with SIMS and the reference measurements. The overall agreement is good, but for 0.25 < x < 0.65, the values of x found by TEM are systematically 0.05 too low. Using the SIMS and reference measurements as a calibration, compositions can be determined by TEM with an accuracy between 0.03 (low x) and 0.05 (high x) in layers as thin as 1.5 nm.

An amorphous-to-fine-grain-polycrystalline phase transformation has been observed during annealing of Sn-implanted Si when the peak Sn concentration exceeds about 2 at.%. At lower Sn concentrations, epitaxial growth is retarded in (100) Si but proceeds to completion with a large fraction of Sn residing on substitutional lattice sites. As the Sn concentration is increased, epitaxy is pre-empted by the sudden transformation of the near-surface Sn-doped region into polycrystalline Si. The time required to initiate the transformation is temperature dependent and is characterized by an activation energy of ∼1.7 eV. Rapid redistribution of Sn has been observed to accompany the transformation. Our observations are shown to be consistent with a melt-mediated crystallization process which is rate limited by Sn diffusion and precipitation in amorphous Si.

The microstructure and mechanical behavior of electroless deposited Ni–P on Al–Mg substrates were investigated. The microstructures of the as-deposited and annealed samples were characterized through optical and scanning electron microscopy. Hardness measurements were made both on the Al–Mg substrate and the Ni–P coating using a depth sensing hardness machine. The plastic deformation behavior of the composites was studied and the results show that the initial deformation is accompanied by the appearance of serrations on load-displacement curves. Decohesion of the hard Ni–P takes place at large strains. An estimate of the ultimate shear strength of the Al–Mg/Ni–P interface was made and the strength of the interface was determined to be −0.45 GPa. The tribological properties of the amorphous Ni–P were studied using ball-on-disk and slider-on-disk tests. In particular, the influences of humidity, surface roughness, and heat treatment on friction and durability of the coatings were investigated.

Nearly single-phase thin films of three different Pt–Ga intermetallic compounds have been grown on GaAs(001) by co-deposition of Pt and Ga. The resultant films have been annealed at various temperatures and then characterized using x-ray two-theta diffractometry (XRD), Auger electron spectroscopy (AES), and x-ray photoemission spectroscopy (XPS). The XRD results showed that PtGa2 and PtGa thin films are chemically stable on GaAs under one atmosphere of N2 up to 800 °C and 600 °C, respectively, but thin films of Pt2Ga react with GaAs at temperatures as low as 200 °C to form phases with higher Ga concentration PtAs2. The XRD patterns also revealed that the crystallite orientation and texture of the films were dependent on annealing temperature. Segregation of Ga to the surfaces of the films upon annealing was also observed by both AES and XPS. The results demonstrated that the as-deposited films of PtGa2 and PtGa were kinetically stabilized with respect to possible chemical reactions with the GaAs substrates that evolve gaseous As species during open system annealing.

The structure of Ti4Ni4Si7 is studied using powder neutron diffraction and Rietveld analysis. Prccise determination of the crystalline parameters, atomic positions, and temperature factors is achieved. A criterion previously elaborated for the phase TiFeSi2 is used to determine the coordination number. From the arrangement of the atoms in the unit cell and their interbond distances, we find that Si atoms are nearest neighbors to Ti and Ni. An extension of the same criterion shows that Ti–Ni and Ni–Si hybridization is likely to be strong while Ti–Ni hybridization is weak. A comparison with mono- and disilicides is made.