Free Surface Side Research Articles

Characterization of Zn-alloyed CdTe compound semiconductors processed in microgravity on USML-1 and USML-2

Three of the four CdZnTe crystals grown on USML-1 and 2 have been analyzed with respect to hydrostatic and buoyant gravitational influences. Characterization was carried out using Synchrotron White Beam X-ray Topography, Fourier Transfer Infrared (FTIR) Spectroscopy and chemical etching. It was found that in the absence of hydrostatic pressure the liquid separated from the ampoule walls, depending on influences such as: volumetric fill-factor, level of constraint, residual g-vector, ampoule geometry and growth conditions. Regions solidified without wall contact were found to be virtually free from twinning, suggesting that these pervasive defects are surface nucleated. Further, these regions showed dramatic reductions in the density of dislocations, from 800,000 (l-g) to 800 (μ-g). This was attributed to thermo-mechanical stress reduction within the flight samples. Regions of partial wall contact showed defect gradients, high on the wall side and low on the free surface side. These results are consistent with our thermo and thermo-mechanical stress model.

Heterogeneity generation by thermodiffusional mechanism in rapidly solidified amorphous alloys

Rapid solidification can produce amorphous alloys and materials with homogeneous and microcrystalline structures. However, chemical, structural, topological and other heterogeneities are frequently observed in rapidly solidified materials. Chemical macro-heterogeneity in melt-spun amorphous alloys is considered in this paper. In binary amorphous alloys (i.e. binary glass metals), it is expressed in rising of metalloid content from the contact side to the free surface side of the melt spun ribbon. The thermodiffusional mechanism of this heterogeneity generation is investigated. A mathematical model of the melt-spinning process was developed and numerically calculated for the case of binary alloys. Simulation of the process showed that the concentration wave appears in the liquid alloy film during its quenching. This wave moves from the contact surface to the free surface, and the concentration heterogeneity is developed before the solidification begins. The amplitude of heterogeneity strongly depends on the thermo-physical properties of the material and the process parameters. The simulation results compare favorably with the experimental observation using X-ray spectral microanalysis.

Al含有Fe-Si-B-C急冷凝固薄帯の組織観察

Microstructures of thick Fe80.5Si6.5B12C1 amorphous ribbons which were crystallized by the addition of 0.01 mass%Aluminum have been examined. The ribbons with the thickness of 66-74 μm were cast by using a multiple slotted nozzle in a conventional single roll method. The microstructures of the as-cast ribbons were as follows: The region near the free surface of the ribbon was fully crystallized. The confirmed phases were primarily α-Fe which forms dendritic structures, Fe2B and orthorhombic-Fe3B. The roll side of the ribbons was primarily amorphous with α-Fe. The middle region in the ribbon thickness direction was primarily amorphous with only a trace of α-Fe. In the free side surface, it was found that (110) orientation of the dendritic α-Fe occurred by the addition of Aluminum and it is considered that the α-Fe formed directly from the molten alloy during casting.

Roughening of Contact Surface During Compressive Plastic Deformation of Polycrystalline Copper.

Roughening of the internal contact surface of polycrystalline copper during compressive plastic deformation is studied. Rectangular split block specimens with initially flat contact surface are pressed against each other. The roughening of the internal surface as well as that of the free side surface is measured with a stylus instrument. It is found that the degree of roughening of the internal surface increases in proportion to the applied strain, but that the magnitude is about half that of the free surface. The detailed shape of the surface roughness curve of the internal surface is different from that of the free surface. From observation with a scanning electron microscope, it is seen that mountains and valleys appearing on the free surface are sharp, while those appearing on the internal contact surface are rather rounded.

An ultrastructural study of the dorsal lingual epithelium of the rat snake, Elaphe quadrivirgata

The histological characteristics and ultrastructure of the dorsal lingual epithelium of the rat snake, Elaphe quadrivirgata, were investigated by light microscopy and scanning and transmission electron microscopy. Most of the surface of the bifurcated part of the tongue was relatively smooth. Dome-shaped, hemispherical bulges were compactly arranged on the epithelial cell surface of the basal area of this region. Intercellular borders were clearly recognizable as striations. Microridges were densely distributed on the epithelial cell surface of the lingual body. Intercellular borders were thickened. A keratinized layer was clearly visible in the epithelium of the anterior bifurcated area, namely, at the apex of the tongue. Although keratohyalin granules were not found in any layer of the epithelium in this area, the cells of the surface layer were filled with keratin filaments. The dorsal lingual epithelium of the posterior area, namely, the lingual body, did not show any evidence of keratinization. Each cell on the surface side still had a large, oval nucleus and intact organelles, such as mitochondria, rough endoplasmic reticulum, ribosomes, tonofibrils, and tonofilaments. Cellular interdigitation was evident between adjacent cells and clear microridges or microvilli were observed on the cell membranes on the free-surface side of cells located in the surface layer. The phylogenetic relevance of these findings is discussed.

Deformation and failure of material being machined upon cutter exit

We study the deformation and fracture characteristics of a material being machined upon exit of the cutter. Steel 30KhGSA and the aluminum alloy D16 are used as the model materials. We describe the techniques and present the results of experimental and numerical modeling of cutter exit. The deformation and the deformation rate and the crack propagation rate in fracturing of the material are evaluated. We show the change of the stress-strain state (SSS) of the material being machined as the cutter approaches the free side surface.

Distortion of injection moulded stainless steel compacts during sintering: T. Takekawa (Ishinomaki Sensu University, Ishinomaki, Japan) J. Japan Soc. Powder and Powder Metallurgy, Vol 40, No 5, 1993, 484–487. (In Japanese)

Powders of Fe-2.20wt.%C-0.85wt.%Si and Fe-4.16wt.%C-0.87wt.%Si alloys were plasma sprayed on a steel substrate in a low pressure chamber. The deposite layers formed on non-water-cooled substrate are composed of stable phases of ferrite and cementite. When the substrate is water cooled, the main constituents of the deposit layers are retained austenite and a metastable h.c.p. ϵ phase on the free-surface side for the respective alloys, and self-annealing occurs to some extent on the substrate side. On spraying, molten powders solidify at a cooling rate higher than 106 K s−1 in the case of a water-cooled substrate, and the cooling rate is larger than that attained in flame spraying. Such a high cooling rate in low pressure plasma spraying is attributed to the fact that the flattened particles which come from the molten powders to produce a deposit layer are thin and that the heat resistance at the interface between the flattenned particle and the underlying deposit layer is small because of the reduced amounts of pores and oxides at the interface.

Sintered copper-aluminium oxide materials for welding electrodes: J. Michalowski et al (Wojakowa Akademia Techniczna, Warsaw, Poland) Metal, Proszkow, Vol 26, No 1–2, 1993, 3–9, (In Polish)

Powders of Fe-2.20wt.%C-0.85wt.%Si and Fe-4.16wt.%C-0.87wt.%Si alloys were plasma sprayed on a steel substrate in a low pressure chamber. The deposite layers formed on non-water-cooled substrate are composed of stable phases of ferrite and cementite. When the substrate is water cooled, the main constituents of the deposit layers are retained austenite and a metastable h.c.p. ϵ phase on the free-surface side for the respective alloys, and self-annealing occurs to some extent on the substrate side. On spraying, molten powders solidify at a cooling rate higher than 106 K s−1 in the case of a water-cooled substrate, and the cooling rate is larger than that attained in flame spraying. Such a high cooling rate in low pressure plasma spraying is attributed to the fact that the flattened particles which come from the molten powders to produce a deposit layer are thin and that the heat resistance at the interface between the flattenned particle and the underlying deposit layer is small because of the reduced amounts of pores and oxides at the interface.

Nanocrystalline Nd12Fe80B6Nb1Ga1 melt-spun ribbon with textured surface

In Nd-Fe-B melt-spun ribbon, Ga addition is found to be effective for the orientation of c axis of 2-14-1 grains normal to the ribbon plane even at high wheel surface velocity. A Nd12Fe80B6Nb1Ga1 melt-spun ribbon quenched with optimum wheel surface velocity was found to have textured structure on the free-side surface. Furthermore, this melt-spun ribbon was composed of fine grains of about 30 nm in size which is believed to be enough to provoke intergrain exchange interaction. The remanence and energy product of the field aligned powder of this melt-spun ribbon was about 7% and 20% higher than those of the not-aligned powder, respectively.

Surface crystallization of metallic glass Fe71Ni3Cr4Si8B14

Surface crystallization happened during ribbon production of metallic glass Fe71Ni3Cr4Si8B14 is studied by means of X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, and Auger electron spectroscopy. Experimental results reveal that the as-produced ribbon has different structures for different layers. Crystalline phases are observed in both the contact side layer and the free surface side layer, although the middle part of the ribbon is still amorphous. The structures of the crystalline phases are determined by means of electron diffraction.

A scanning Auger microprobe study of the surface layer of FeCrPCSi amorphous ribbons

We present a study of the surface oxide layer of industrially air-produced FeCrPCSi amorphous ribbons. Ion bombardment assisted-SAM (Scanning Auger Microprobe) was used to characterize the layer. It was found that the free side surface layer is heterogeneous and consists of (silicon, titanium) rich oxide tiles embedded in an iron oxide matrix, whereas the wheel layer was evaluated for both sides of the of iron oxide. Using depth profiling, the thickness of the surface layer was evaluated for both sides of the ribbons, including the tiles. It was shown that it was less than 30 nm everywhere.

液体急冷Al基正20面体相の集合組織

X-ray pole figures have been measured for icosahedral Al68Si4Ru8Mn20, Al100−xMnx x=21, 17, 14, Al60Li30Cu10 and Al65Cu20Fe15 quasicrystals produced by melt-spinning. Single icosahedral phase was obtained for the samples except for Al100−xMnx x=17 and 14. In the two samples, fcc-Al phase coexists.In the samples consisting of single icosahedral phase, the 5-fold axis is preferentially alligned in the direction normal to the ribbon surface. The observation of the cross section of the ribbon by SEM has shown that grains of this phase grow columnarly from a roll side surface to a free side surface. These results lead to the conclusion that the direction of the columnar growth is parallel to the 5-fold axis.In the samples which contain the fcc-Al phase, no texture is observed for the icosahedral phase. Instead, a (111) texture is found for the fcc-Al phase. The absence of texture for the Al-Mn, icosahedral phase is consistent with the observation that most of the grains in the icosahedral phase are spherical.

Fine structure of the dorsal lingual epithelium of the lizard, Gekko japonicus (Lacertilia, Gekkonidae)

Three different types of lingual papilla were observed by scanning electron microscopy on the dorsal lingual epithelium of the lizard Gekko japonicus. Dome-shaped lingual papillae were located at the apex. Flat, fan-shaped lingual papillae were seen in the widest area of the lingual body. Long, scale-like lingual papillae were arranged on the latero-posterior dorsal surface. At higher magnification, microvilli and microridges were seen to be widely distributed over the surface of the papillae. By light microscopy, the epithelium of the dome-shaped papillae was composed of single, columnar epithelial cells filled with secretory granules. The tip of the epithelium of the fan-shaped and scale-like papillae was composed of stratified squamous epithelial cells without granules. The major part of the epithelium of these two types of papilla, except the tip area, was also composed of single, columnar epithelial cells with secretory granules. By transmission electron microscopy, a nucleus without a defined shape was seen to be located in the basal part of each of the single, columnar epithelial cells. Rough-surfaced endoplasmic reticulum and Golgi apparatus were well developed around the nucleus. The other, major part of the cytoplasm was filled with the spherical secretory granules, a large number of which had very electron-dense cores and moderately electron-dense peripheral regions. In the stratified squamous epithelium, a nucleus, which tended to be condensed on the free-surface side, was located in the center of each cell. Mitochondria, endoplasmic reticulum, and vesicles were observed in the cytoplasm.

Rapid solidification and self-annealing of FeCSi alloys by low pressure plasma spraying

Abstract Powders of Fe-2.20wt.%C-0.85wt.%Si and Fe-4.16wt.%C-0.87wt.%Si alloys were plasma sprayed on a steel substrate in a low pressure chamber. The deposite layers formed on non-water-cooled substrate are composed of stable phases of ferrite and cementite. When the substrate is water cooled, the main constituents of the deposit layers are retained austenite and a metastable h.c.p. ϵ phase on the free-surface side for the respective alloys, and self-annealing occurs to some extent on the substrate side. On spraying, molten powders solidify at a cooling rate higher than 10 6 K s −1 in the case of a water-cooled substrate, and the cooling rate is larger than that attained in flame spraying. Such a high cooling rate in low pressure plasma spraying is attributed to the fact that the flattened particles which come from the molten powders to produce a deposit layer are thin and that the heat resistance at the interface between the flattenned particle and the underlying deposit layer is small because of the reduced amounts of pores and oxides at the interface.

Characterization of the AIN–W Interface in a Cofired Multilayer AIN Substrate

The AIN–W Interfaces in a cofired multilayer AIN substrate were observed using an optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Optical and SEM observations showed an intricate intricatelocking AIN‐W grain structure at the interface. After the W pad was removed from the substrate with a NaOH etchant, the surface morphology of the W metal at the interface side was found to be very rough, with a small‐grain microstructure compared with that at the free surface side. Electron microprobe analyses using SEM revealed that there was no diffusion of either W or Al at the interface at the order of a few micrometer's resolution. Bright‐field images, dark‐field images and selected area electron diffraction (SAD) patterns using TEM indicated there was no secondary phase between AIN and W. However, scanning transmission electron microscopy using an energy dispersive X‐ray detector revealed that there was a 200‐nm thick W diffusion layer from the interface into the AIN ceramics. It was concluded that the high adhesion strength between the W conductor and the AIN substrate (>20 MPa) was not due to any secondary phase but to mechanical interlocking of AIN and W during cofiring.

Effect of melt spinning on grain size and texture in Ni-Mo alloys

Chill block melt spun ribbons of nickel molybdenum alloys with molybdenum contents of 8 to 41.8 wt pct Mo have been examined for their microstructure and texture dependence on processing conditions. Linear features observed in grains solidified with a planar liquid-solid interface at the quench side of the ribbons have been identified to be due to the twins on (111),, plane formed during solidification. Grain size variation with the wheel surface speed and the alloy composition has been studied. Crystallographic texture on quench side and free surface side of the ribbons has been investigated.

微量TiによるFe-B-Si系非晶質合金の磁気特性の劣化

The impurity Ti (0.02-0.2 mol%) in Fe-B-Si amorphous alloys prepared by the melt spinning method was found to deteriorate extremely the iron loss, W13⁄50, and the magnetic flux density at 100 A/m, B1.When the Ti concentration in an amorphous alloy strip was more than 0.05%, the α-Fe crystalline layer was detected on the free-side surface of the as-cast strip by X-ray diffraction, but not on the roll-side surface. This surface crystalline layer results partially in the deterioration of the magnetic properties through the magnetostriction, because it applies the compressive stress to the strip. According to X-ray diffraction and differential thermal analysis, the as-cast strip was in an amorphous state except the surface crystalline thin layer.The magnetic property of Ti-containing amorphous alloy strip annealed in the magnetic field was not improved to the extent of the pure Fe-B-Si amorphous strip, even after removal of the surface crystalline layer by chemical polishing. The internal magnetic field and the direction of the magnetic moment in the amorphous alloys changed with the addition of a small amount of Ti according to the Mössbauer spectra, so it was suggested that the main mechanism of the deterioration was the solute Ti in the amorphous alloys, but not the crystallization.

On the Non-Uniform Deformation of Material in Axially Symmetric Compression Caused by Friction : Part 2, Theoretical Analysis of Compression of Circular Cylinder by the Finite Element Method

Non-uniform deformation of an elastic, strain-hardening circular cylinder in axial compression is analyzed by the finite element method. Deformation is pursued from elastic through partially plastic to totally plastic stages, allowing for the finite deformation or geometrical change of the material coordinates. As the boundary conditions, the experimentally determined values of the slip-ratio which was proposed by the authors are used instead of the conventional friction coefficient. Calculations of 23 cases are performed for various combinations of lubrication and height to diameter ratio. As the result, the followings have become clear: shape of bulge of the free side surface, relation between the load and the compressive strain, distribution of normal pressure and tangential stress together with the friction coefficient on the boundary surface, mean friction coefficient, patterns of appearance, growth of plastic zones, etc. These results are qualitatively in agreement with the theoretical results which were presented in Part 1 of this series of investigation; i.e. the results obtained by applying variational principle. Agreement with the experimental observations is also satisfactory.

Motor innervation of the fetal rat tongue; its development, function, and significance in the mechanism of palate closure

The histology and morphology characteristics of the tongue in Scincella tsinlingensis were studied by light and electronic microscopy. Under light microscopy, the tongue consists of tip, lingual body and radix in sequence. Numerous lingual papillae widely distribute on the surface of the dorsal and ventral flanks in the tongue, in addition to some regions of the tip. The papillae’s surface is covered with the epithelial layer. The lamina propria and dense connective tissue are distinct existing under the epithelial layer. There are many lingual glands spread over the lamina propria. Tongue muscle is developed and composed of distinct intrinsic muscle, hyoglossus and genioglossus. By scanning electron microscopy, at higher magnification, the epithelial cells of the dorsal surface in the divaricate tongue tips show numerous microvilli, micro-ridges and micro-pores. The surface of dorsal side of the papillae in lingual body is covered with abundant of micro-ridges and taste bud lacuna. On the surface of the papillae in radix, micro-facets and micro-ridges are compactly distributed, as well as scattered mucilage-pores. The lingual epithelium is divided into four layers observed by the transmission electron microscope. Cells of basal layer are irregularly elliptical in shape, with sparse organelles in the cytoplasm. The deep intermediate layer is not always distinct. Small numbers of organelles are scattered into the cytoplasm. The cells of the superficial intermediate layer gradually flatten, as do their nuclei. The cytoplasm contains many keratohyalin granules. Cell membranes are formed processes around cells and joined by abundant desmosomes to the cell membranes of adjacent cells. The cells located on the extreme free-surface side of the keratinized layer have fallen off. The basal lamina is intercalated between the basal layer and the lamina propria. The lamina propria of lingual body contains lingual gland. A large part of the cytoplasm is occupied by mucus granules which located in the distal part of the cell. The connective tissue contains myelinated nerve fibers, vessel and muscle cells.