Fine Inclusions Research Articles

Elongation of a body with an array of fine elastic inclusions

Elongation of a body with an array of fine elastic inclusions

Solution of an elasticity problem for an unbounded solid with a coplanar system of fine inclusions

Solution of an elasticity problem for an unbounded solid with a coplanar system of fine inclusions

The sedimentary history of a debris‐flow dominated, Devonian alluvial fan–a study of textural inversion

ABSTRACTKarlskaret fan, with a radius of less than 11/2 km and dominated by debris‐flow conglomerates, is one of numerous alluvial fans built out from the fault margins of Hornelen Basin (Devonian, Norway). The fan body is more than 170 m thick proximally, consists of four main coarsening‐upwards segments and thins distally by a rising of its base and by a vigorous interfingering with very fine‐grained sediments originating from an adjacent, impinging floodbasin system.Within the entire fan body, and within individual lobes, is a proximal‐distal (and vertical) facies change from sheet‐like, polymodal debris‐flow conglomerates through matrix‐rich conglomerates that are commonly distorted by loading, slumping and faulting, to remarkably sheet‐like, matrix‐rich granule sandstone of subaqueous debris‐flow origin.Because the alluvial fan prograded into an actively aggrading floodbasin the primary fanglomerates, themselves having been subject to some sorting on the fan surface, incorporated large quantitites of very fine sediments. This inclusion of fines, effectively a textural inversion on the lower fan reaches, frequently led to remobilization and resedimentation of material beyond the fan toe. Anomalous maximum particle size/bed thickness relationships and a variety of graded textures within these resedimented beds suggest deposition in lacustrine areas of the adjacent floodbasin.

各種鉱床産錫石中の微量成分, 格子定数および磁性について

22 pure cassiterite samples were collected from the Indonesian tin placers and from the typical tin mines in Japan. Quantitative analysises were carried out by atomic absorption for Fe, Co, Ni, In, Pb, Mn, Ti, W and X-ray fluorescence for Zr, Nb, Ta.From the analytical results and the magnetic property, the following conclusions were drawn.1) The Fe, Nb, Ta, W, Ti and Zr contents in cassiterite have a relatively large variance in each sample, while the Co and Ni contents are low and constant. The other elements, as Mn, In and Pb, are a few hundred of ppm at most, showing the median behavior between the two groups above.2) The placer tin in Indonesia has generally the high contents of Fe, Nb and Ta, being characteristic in the existence of Y, Th and lanthanid elements.3) The unit cell volumes of cassiterites are constant against increasing total impurities in cassiterite (SnO2).4) The weak ferromagnetism in cassiterite could be attributed to the very fine inclusions of, Fe oxide mineral such as magnetite.

Determining the stress concentration in an elastic body with a system of fine inclusions located in the same plane

Determining the stress concentration in an elastic body with a system of fine inclusions located in the same plane

INCLUSIONS IN BONE MATERIAL AS A SOURCE OF ERROR IN RADIOCARBON DATING

Electron probe microanalysis, x-ray diffusion and microscopic examination were conducted on bone material from several archaeological sites in order to identify post-burial inclusions which, if present, may effect radiocarbon dating of bone. Two types of inclusions were identified: (1) precipitates from ground water solutions, and (2) solid intrusions. The first type consists of calcite, pyrite, humates? and an unknown material. The second type includes quartz grains, hyphae, rootlets, wood, and charcoal. Precipitation of calcite in a macro-molecular level in bone may lead to erroneous dating of bone apatite if such calcite was not removed completely. A special technique, therefore, must be employed to remove calcite completely. Hyphae and rootlets also are likely to induce errors in radiocarbon dating of bone collagen. These very fine inclusions require more than hand picking.

(C) Internal oxidation of steel

High-temperature oxidation of steel is common, although admittedly complex. The product is a surface scale which develops a more-or-less distinct boundary with the under lying metal. Under appropriate conditions, oxygen penetrates beyond the scale and further into the steel to form a dispersion of relatively fine oxide inclusions. Generally, this zone of non-metallic inclusions is rather sharply delineated and is sometimes called subscale. The term ‘internal oxidation’ is used to describe the origin of such a subscale.

Trace element content of metals from L-group chondrites

Eight L- and one LL-group chondrites were selected for a major and trace element content study of their metals by instrumental neutron activation techniques. The elements Ni, Co, Fe, Cu, As, Ga, W, Au and Ir were determined. For each meteorite three metallic fractions were analyzed: (1) coarse, >100 mesh; (2) intermediate, 100–200 mesh; (3) fine, <200 mesh. The composition of the metals varies considerably with grain size, as a result of a preferential concentration of kamacite in the coarse and of taenite in the intermediate and fine fractions. A third metallic component, consisting of very fine plessitic inclusions, was observed in chondrules of equilibrated chondrite types 5 and 6. This component is probably responsible for the decrease of Ni, Cu, Ga and Au observed in the fine metallic fractions of the equilibrated chondrite types. W, as well as Ga, increases in the bulk metals with the petrologic type, suggesting that a substantial amount of this element, as already observed for Ga by previous authors, is not in the metal, but in some silicate phases in the lower metamorphic petrologic types 3 and 4. Ir is always concentrated in the fine metallic fractions of all meteorites, independent of petrologic type, suggesting the presence of a fine-grained metallic component enriched in this element.

Fracture toughness of powder forged Cr-Mn alloy steels

The fracture characteristics of a powder forged Cr-Mn alloy steel have been evaluated by plane strain fracture toughness tests. The toughness values obtained have been related to the distribution of non-metallic inclusions that result from different thermal and mechanical treatments. A comprehensive study was made of the inclusions. Two basic types were found: coarse inclusions > 10 μm were manganese silicates or alumino-silicates, while fine inclusions (∼1 μm) were oxide spinels or manganese (alumino) silicates. These finer inclusions were found to strongly influence the fracture mode and toughness of the material. It is believed that these coarse and fine inclusions formed at different periods during processing of the powder. Ways to optimize the fracture toughness of these powder forged parts are considered.

Properties and microstructure of nickel and nickel-alloy wire produced by working sintered blanks

1. A study was made of the mechanical properties of 3-,2-, and 1-mm-diameter wires (reductions of e = 35, 55, and 75%, respectively) in unalloyed nickel and nickel alloys, produced by powder-metallurgy techniques from carbonyl nickel powder. 2. The mechanical properties (σV,σS,δ, and number of bends n) of such wire in the work-hardened condition are determined by its degree of cold deformation: The maximum values of strength (σV andσS) and the minimum values of ductility characteristics (δ and n) correspond to the highest value ofe, i.e., 75%. 3. The elongation and number of bends of wires of all diameters gradually improve as the annealing temperature is raised from 500 to 700°C, which can be ascribed to both propagation of recrystallization processes and a slight refining of metal brought about by annealing in a hydrogen atmosphere with a dew point of between −35 and −40°C. 4. The mechanical properties of 1-mm-diameter wire (e = 75%) in alloys with fine oxide inclusions vary within a narrow range and, in spite of substantial differences in recrystallization temperature, depend only little on alloy composition, which is due to the severe deformation of the materials and the effect that such deformation has on dispersion-hardened alloys. 5. A Ni + 4% W alloy has a high recrystallization temperature, and, because of this, wire in this alloy retains its high strength and low ductility properties right up to an annealing temperature of 700°C. 6. Unalloyed-nickel and nickel-alloy wires produced by cold-working sintered blanks can be successfully used in either the work-hardened or annealed condition. Heat-treatment parameters must be chosen individually for each specific type of operation.

Platy α-SiC Single Crystals Grown from Silicon Solution

Platy α-SiC crystals, 2-3mm in diameter were obtained by the method. Growth experiments were performed using purified dense graphite crucible (bulk density>1.80) and high pure silicon as a solvent at 2200°C for 5 hours or less.These crystals were consisted of mainly 6 H type. The probability to form wurtzite type twinning, the angle between basal plane being ca. 70°30′ in these crystals is less than that in these obtained by sublimation method.Though some of the crystals include very thin silicon layer, generally these inclusions show a tendency to localize in a part of a crystal. Fine and dispersed inclusion such as carbon particle in the crystals by sublimation method is not observed in these crystals. The relation between the polality of the basal surfaces and their growth rate is studied by chemical etching, and it is suggested that there is reverse relation between crystals grown from silicon solution and sublimation.

Investigation on Abnormal Brittleness of High Density Sintered Iron

It has been reported by H. Kuroki and Y. Tokunaga that most of the commercial iron powders represent an abnormal brittleness, mainly grain boundary rupture and partly cleavage, in the density range of 6.8-7.3 g/cc. In the present work some attempts were made to clarify the cause of these brittle ruptures.It was concluded that the abnormal brittleness is caused by a remarkable grain growth in the density range around 7g/cc. Based on the experimental observations, two different mechanisms of embrittlement are considered.First, the embrittlement can occur through the enhancement of the ductile-brittle transition temperature caused by grain growth, as was observed in the case of electrolytic and millscale iron powders, which is well known on ferritic steel.The second mechanism is due to a grain boundary rupture and observed on reduced ore powder. This type of rupture was observed even at high temperatures (>150°C). Although a large number of fine nonmetallic inclusions are contained in reduced ore iron powder, the volume fraction and the notch effect of these inclusions seem to be relatively smaller than those of the residual pores in the sintered iron structure. Therefore, the brittleness of the coarse grain structure of the reduced ore iron powder compact could be of the same character as low temperature brittleness, but abnormally expanded to high temperatures with a largely diffused transition temperature.

On the Structure of a Hen's Egg Yolk and Yolk Spheres

1. Yolk of a egg was fixed with 10% acrolein-0.05M phoshate buffer (pH 7.4) of LUFT11) by keeping in a cold dark place for 5-7 days and frazen sections of 3-7μ thickness, usually of 5μ, were prepared. Some of the sections were stained for lipid with Sudan IV or Sudan Black B-55% ethanol solution, 1% Nile Blue A solution, or BAKER'S acid hematein. Other sections were post-fixed with the HELLY solution and stained with Azan or extracted with pyridine and submitted to the SCHIFF reaction (acrolein-SCHIFF reaction).Experimental hens were given diet mixed with Sudan IV or Sudan Black B, or given intravenous injection of dye colloid solution, and the time the yolk spheres were formed was presumed from the striations of the dye formed inside the yolk.The shape of striped patteren of the dye in the yolk seemed to suggest that there might be a kind of potential flow in the growing yolk and a test was made with an electrical model. For the circuit, a KOHLRAUSCH bridge used in hydrodynamics was employed. A brass ring was provided with insulators corresponding to the blastodisc and a highresistance part corresponding to the periphery of the blastodisc, and 10% sodium chloride solution was filled inside the brass frame. An electrode was placed in the center of the ring, and a weak alternating current was passed to such a degree that there would not be any heat generation. Resistance in the high-resistance part was varied to obtain isopotential curves.2. White yolk spheres are distributed in latebra, neck of latebra, nucleus of Pander, and yolk surface layer around the blastodisc, and only yellow yolk spheres were observed in other parts. Yolk spheres in the surface layer of the yolk were medium to small yellow yolk spheres except around the blastodisc. Primordial yolk spheres were distributed from the center of latebra to the part adjacent to the blastodisc, becoming smaller as they approached the blastodisc and forming a vacuole in the inclusion and finally formed a mass of foams.3. White yolk spheres were varied in shape; from a primordial yolk sphere of 3-25μ diameter containing one drop-like inclusion to that of around 40μ containing numerous fine droplet inclusions. The inclusion substance tended to become smaller and more numberous with increase in the diameter of the spheres. On the other hand, yellow yolk spheres were 30-150μ in diameter and contained numerous fine granular inclusions, which were sometimes more coarse.There was no difference in the stainability of the inclusions of these two kinds of yolk spheres, and the staining indicated that the main component was a protein, with a small amount of phospholipid. Stainability of the matrix was also similar in the two spheres and indicated the presence of a large amount of fats besides the protein. Numerous fat drolets showing the characteristic of a neutral fat were observed but they were very fluid and their localization could not be clarified.The greatest difference between these two kinds of yolk spheres lies in the concentration of phospholipid in the matrix. While the matrix of white yolk sphere was almost negative or weakly positive to acid hematein, that of yellow yolk sphere was strongly positive to it.4. Layered structure was invariably seen in the latebra in which primordial yolk spheres and slightly large yolk spheres were arranged alternately. As a whole, the structure resembled the form of yellow yolk spheres nearer the outer layer. The layer of yellow yolk spheres in the outer side of the latebra showed layered changes in the degree of stainability but majority of hen eggs showed approximately uniform structure, irrespective of yellow or white yolk layer.5. The continuous phase between yolk spheres was fairly marked in the site where primordial yolk spheres were present and extremely small in the site with the other yolk spheres. Its staining characteristics indicated the presence of a small amount of protein.

Implementation of a laboratory batching procedure with a correction for fines and moisture

The selection of an appropriate aggregate structure is a key step during mix design since this directly affects mix performance and the amount of asphalt in the mix. During conventional batching procedures, the aggregates are dried and sieved into different sizes only to be recombined later into the appropriate proportions to reproduce the design gradation. This type of procedure can produce gradations with substantially larger percent passing the sieve No.200 relative to the target gradation. This paper explores the effects that fines adhered to larger particles have on the batch gradation, the resulting optimum binder content and dust proportion. An improved batching procedure that corrects for fines adhered to larger particles and trapped moisture is presented in detail and shown to replicate the target design gradation more closely. The optimum asphalt content was determined by means of the Superpave® design method for both, a gradation batched conventionally and a gradation batched with the suggested corrected procedure. The results show that the optimum asphalt content and volumetrics obtained in both cases are substantially different. The procedure developed for the fines correction is recommended for routine batching in order to minimize the inclusion of additional fines that can potentially affect the performance characteristics of the mix.

The effect of nonmetallic inclusions on the fatigue strength of quench-hardened steel

1. The current metallographic method of evaluating the degree of contamination of steel does not give a sufficiently accurate indication of the nonmetallic inclusions content, particularly in high-grade, electroslag- and vacuum-melted steels. This is mainly because this method fails to take into account the very fine nonmetallic inclusion particles. 2. Since very small nonmetallic inclusions have the same harmful effect on the fatigue strength of high-purity vacuum- and electroslag-melted steels as microporosity, voids, and other crystallization defects, the density of steel will serve as a criterion of its degree of contamination and hence its quality. 3. Studies of hydrogen embrittlement of steels under review prove that they contain large proportions of fine nonmetallic inclusions and crystal defects, which are not revealed by the standard method of evaluating the purity of steel, but are reflected in its density. 4. In the absence of surface stress risers, the fatigue strength of steel depends upon its purity. As the concentration of nonmetallic inclusions and crystallization defects decreases, i.e., as the density of the steel increases, its fatigue limit increases. 5. The total content of nonmetallic inclusions and crystallization defects in electroslag-melted steel is lower than in vacuum-melted steel; thus the former has a higher fatigue limit. 6. So far density has never been included in the properties specified for type ShKh steel. In view of the experimental evidence cited above, this property is an important criterion of the purity of steel and, as such, should be included in specifications relating to the fabrication of high-purity, electroslag- and vacuum-melted steels.

The effect of fine nonmetallic inclusions on the mechanical properties and recrystallization of sintered metals

A study was made of the influence of fine silica and alumina inclusions, which are irreducible under sintering conditions, on the sinterability, mechanical properties, and recrystallization of dense sintered nickel.

The Applicability of Theoretically Calculated Intensity Corrections to Practical Metallurgical Problems in the Electron Probe

AbstractRecent studies have indicated only limited agreement between theoretically calculated X-ray absorption, fluorescence, and electron penetration correction factors and calibration curves obtained from alloy standards in binary systems. For some practical metallurgical problems, including diffusion gradient studies, intermediate phase identifications, etc., where analytical precision is required, alloy standards must be employed.Most metallurgical investigations, however, are concerned with alloys containing a variety of elements. The use of theoretical calculations in these analyses is severely limited. At present, the precision of analyzed chemistries in such systems is somewhat poorer than the precision of the measured X-ray intensity values. Methods for applying combinations of theoretically calculated corrections, extrapolations from nominal alloy chemistries, etc. have been employed which yield reasonable analytical precisions but at best are first-order approximations. Approximate calculations for use in determining the chemistries of fine precipitates or inclusions where matrix excitation is unavoidable are also discussed.