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Airborne measurements of cloud condensation nuclei (CCN), total particle counts, the size distribution of particles, and the microstructure of warm clouds have been made in the vicinity of a large Kraft pulp and paper mill. The plume of CCN and total particles from the mill is well-defined at distances up to 40 km downwind and the concentrations of these particles reach values which exceed those in the ambient air by a factor of about 4. A large peak in the concentrations of CCN was measured in the plume at a distance downwind of the mill corresponding to a travel time of about 4 hr. The total particle count in the plume peaked after about 2 hr of travel time downwind. The particles in the plume were measured over the size range 0.3 to 8 μm; their concentrations were much higher than in the ambient air, particularly those with diameters

We have investigated the role of polymerization degree on the surface microstructure of insulating paper for power cable by means of the electronmicroscope.When the pulp of _??_ 1, 650_??_445 is beaten to SR 40°, in the case of _??_ 1, 650, the surface is covered with S1 wall layer and internal fibrillation of S2 wall layer is incomplete. In _??_ 1, 270, it is clarified that most part of the S1 wall layer is separated, and fine internal fibrillation parallel to the fiber axis is found. In such a microstructure, the values of the mechanical and electrical properties are found higher.Under the _??_ 1, 000, fiber was partially cut and broken during beating, and then mechanical strength of paper was lowered. Moreover, it appears that the fibrillation of S1 and S2 wall layer is disproportionate. But most of the S2 wall layer is internally less fibrillated, and the microstructure on the surface disordered.

There exist two kinds of methods for pulp refining ; that is, the low consistency refining and the high consistency refining. The low consistency refining method (LCR) has been conventionally used, but it has proved to damages and shortens the fibres. On the other hand, the high consistency refining (HCR) loosens the fibre structure and makes it flexible with a minimum of fibre damages, despite of the fact that HCR method requires more power in order to produce papers of maximum strength. This paper presents comparisons between these two methods from the following points of view. (1) Comparison of paper formation measured by the Bata-Radiograph method. (2) Comparison of the microstructure of the fibre by the scanning electron micrographs. (3) Comparison of dry paper physical properties. Our experiments have demonstrated the following. (1) The scanning electron micrographs of paper produced by each different rifining method show different shapes of fibre : In LCR method the outer layer of the fibre is removed in the lumpy shape, while external fibrillation of the HCR fibre is seen extensively and the fibre surface becomes fuzzy. (2) The paper formation by LCR method becomes poorer with high beaten pulp and the paper formation by HCR method grows better with high beaten pulp on the contrary to our expectation. (3) Uniform refining is a most necessary to obtain paper of good formation.

In the first section of this paper it is pointed out that one and the same metal may cause a great variety of different colours, just as the colour of gold vapour differs from the colour of the light reflected from gold as well as from the colour of the light transmitted by gold leaf. While the ultimate cause of the colour of a metalliferous medium is to be found in the structure of the metal molecule itself, the arrangement of these mole­cules, according to any fixed law, causes them to affect one another’s free periods in a definite manner, and thus gives rise to corresponding optical properties. The object of this paper is to discover, by means of these optical properties, the molecular arrangement (microstructure) of various metal glasses, of colloidal solutions of metal and of metallic films. Expressions giving the refractive index and the absorption coefficient (the optical constants) of a compound medium consisting of metal (1) in small spheres (granular), and (2) in discrete molecules (amorphous), diffused through an isotropic non-dispersive transparent medium (the solvent), are next investigated in terms of the corresponding optical constants of the normal metal.

When strained, with or without subsequent heating, many metals produce twinned markings. It is customary to call the former mechanical twins and the latter annealing twins. According to Dana “ twin crystals are those in which one or more parts regularly arranged are in reverse position with reference to the other part or parts.” This must be held to apply not merely to the external symmetry of crystals which possess plane faces, but also to the internal symmetry of such substances as metals and alloys. which do not possess plane faces. Metallic crystals may result in one of several ways. They are formed, e. g., by solidification from the liquid state, a process which is known as primary crystallisation, and results in the formation of crystallites, or they are produced by rearrangement of the atoms in primary crystals giving rise to what may be termed secondary crystals. This term includes such phenomena as crystal growth, recrystallisation, polymorphic transformation, etc. Primary crystals which have solidified in such a way that they are unstrained do not contain twin crystals. The phenomenon is confined to the various types of secondary crystals just mentioned, and, therefore, appears to be related to what may be called atomic rearrangement. The present paper describes observations made on annealing twins, mainly those of copper and its alloys. It has arisen as a result of what the authors have found and described in another paper, viz., that it has proved impossible to prepare large copper crystals by the method of critical straining and annealing without at the same time producing twin crystals. Experiments . The copper used was commercially pure “ high conductivity ” metal in the form of cold rolled strip. The distorted crystals contained numerous twins which had been produced by repeated annealings and rollings during manufacture. When the strip was heated in an atmosphere of nitrogen at a temperature of 800° C. for six hours, complete recrystallisation occurred with the production of equiaxed crystals. Subsequently the strip was deformed to a very slight extent and again heated at 800° C. for six hours, after which the small equiaxed crystals were completely converted by crystal growth into a few large crystals. Representative microstructures of the strip as received, after crystallisation and crystal growth, are shown in photographs Nos. 1, 2 and 3, at a magnification of 80 diameters. It will be noticed that the crystal size increases markedly under the above treatments, and, in fact, No. 3 represents only a portion of one copper crystal which, however, contains twin crystals oriented in three directions. It will be noticed that all three photographs show the presence of twins. They may either appear light on a dark crystal or dark on a light crystal; they may extend right across a given crystal or over only a part of it. Further, they vary very considerably in thickness. These photographs show that the twinned crystals in copper which are present in the originally cold worked metal are neither removed by recrystallisation nor by subsequent crystal growth, although during the former process all the old crystals are replaced by new ones, and during the latter a large number of crystals are absorbed into a few large ones. Photograph No. 4 represents an area, part of which has undergone recrystallisation (small crystals), and the remainder crystal growth in addition. The multiple twinning shown in the large crystals is very striking.

In the previous papers, the authors investigated the change in residual stress and microstructure in relation to the change in half-value breadth of annealed carbon steel in fatigue process, adopting (310) diffraction line. Based on the results of the experiments, the following conclusions were derived. Slip traces appear as regularly arranged line in the special slip planes of certain crystal grains in the early stage of alternating stressing, and they grow longer and wider with the increase of the number of cycles. In this period, both half-value breadth and compressive residual stress increase rapidly. It was considered that the broadening of half-value breadth comes from the accumlation of dislocations that occurs predominantly on the slip plane {110} by cross slip mechanism. In other words, it may be assumed that the extrusion and intrusion phenomena occur and the fatigue damage proceeds mainly by Cottrell and Hulls mechanism, and this also causes compressive residual stress to generate. In the second stage of fatigue, the half-value breadth increases gradually, while compressive residual stress decreases steeply and thereafter no change cccurs till fracture. Micro-structure shows distinctly that slip bands spread in the limited zone in certain grains. We may assume that micro-cracks initiate in these active slip bands and they promote the development of the visible cracks.However, there are two sorts of ploblems regarding the above investigation made by the authors. The first is that; in order to obtain an experimental proof to support the previous discussion, direct observations of the micro crack, extrusion, intrusion and cross slip phenomena are to be made in fatigue processs for present material. The second is that; according to the extrusion and intrusion mechanism, it is expected that the X-ray diffraction plane dependency of the change in half-value breadth and that of the changes in residual stress are present. In these connections, the authors attempted to investigate the relation between changes in half-value breadth diffracted from several atomic planes (310), (211), (220), (200) and (110), and changes in residual stress obtained from different lines of (310), (211) and (220) atomic planes. Specimens used in these series of experiments are annealed and electro-polished 0.07% carbon steel plate. A reversed bending fatigue testing machine was used for the fatigue test, and the speed of repetitions was 1700 cycles per minute. Residual stress was measured from (310), (211) and (220) diffraction lines, using CoKα1 and CrKα1 radiations, adopting the well known two exposure method at vorious numbers of stress cycles. The CoKα radiation was used to measure the change in half-value breadth of (310), (220), (211), (200) and (110) diffraction lines due to stress repetitions by normal X-ray diffractometer arrangement.Obtained conclusions are as follows;(1) Cross slip traces, extrusion and intrusion phenomena appeared extinctly in the first stage of fatigue stressing in the certain grains, and intensified gradually with increasing number of stress repetitions.(2) Micro cracks initiate in active bands zone, namely, it is observed obviously by electronmicroscope at the bottom of the intrusion slip at the stage of transition point from first stage to second. This micro cracks developed into visible cracks which lead to fracture during the second stage of fatigue.(3) The changes in half-value breadth of (220) and (211) diffraction lines during stress repetitions are quite similar to that of the (310) diffraction line which has been pointed out in previous papers. However, (200) diffraction line width changes greatly and that of (110) is a little in fatigue process.

Few researches have been published on variation of properties of Al-Mg alloy with lapse of time of aging at 50-70°C. Otto Dahl and Klaus Detert recently published a very interesting paper relating to the problem.In this paper, it is found that any marked variation of mechanical and physical properties such as hardness, electrical resistance, lattice constants, etc. could not be seen, when aged at at room temperature or thereabout. As the cause of these phenomena, the contiguity of atomic number of aluminium and magnesium are suggested (13 and 12 respectively).The authors also treated this problem:Alloy specimen were prepared by alloying four nine aluminum with magnesium and mischmetal, the composition of the first series being 2.5, 3.5, 5, 7, 10 and 12% of Mg, and of the second series 5, 7, 10 and 12% Mg with 0.3 and 0.5% of mischmetal. The small specimen of sheets, 1.2mm thick, were solution treated at 400°C, for 2 hours, then quenched in the water (1°C) and then aged at 50, 80 and 100°C for about 3, 000 hours.During aging, hardness, microstructure, electrical resistance and corrosion resistance were intermittently tested. The corrosion resistance was tested by Mylius method; the specimen was immersed in 10% HCl water solution and the amounts of evolved hydrogen were measured.As the results of the study, a marked variation of corrosion resistance was found. When corrosion resistance is represented by “Reaction Number” (RN), or quantity of hydrogen evolved per unit area and per unit time, its variation is shown in Fig. 6 and 7.In other words, RN is smallest at as quenched condition, then rapidly increasses with the lapse of aging time and after passing through the maximum, it decreases on the contrary.Corresponding to the variation of RN the hardness curve has also its inflexion point near the aging time of the maximum RN.These changes probably suggest a formation of some special arrangement of magnesium atoms among aluminium space lattice or of an arrangement similar to Guinier-Preston Zone.

The Research Institute For Iron, Steel and Other Metals. Tohoku University. Effects of the roughness of graphite substrate on the properties of pyrolytic graphite have been examined. Pyrolytic graphite is obtained by pyrolysis of commercial propane gas at the deposition temperature of 2025°C, the pressure of 10mm Hg and the flow rate of 640cc/min by direct heat method. The three kinds of roughness of the substrates are obtained using of abrassive papers (05, 280). The effects are not remarkable as compared with that of the deposition temperature and gas pressure, but can not be ignored. In the case of the smooth surface (abrassive paper 05), the surface of the deposit is smooth and the microstructure is fine, in which the crack does not appear. Furthermore, the formation rate is large, the ordering is good and the preferred orientation is remarkable. But in the case of the rough surface, the above mentioned phenomena tend to appear in the reverse side. Especially, the electrical resistivity of c-axis in the smooth case is about 10per cent higher than that of the rough surface. However, there are inconsiderable difference in the lattice constant and density between the smooth and rough surfaces.

In the previous paper (J. Ceram. Assoc. Japan, 68 [10] 223 (1960)) the authors reported that some glasses of low lithium content (4%) in the system Li2O-MgO-Al2O3-SiO2 could be converted, by the heat treatment, into a polycrystalline material without showing any appreciable deformation even if no special nucleating agent, such as platinum, was added. The present paper contains the results of experiments designed to determine the optimum conditions of heat treatment of the glass of this type for producing a polycrystalline material of high mechanical strength.(1) Chemical composition of the glass studied The glasses of the composition, MgO x, Al2O3 y, SiO2 z, Li2O 4, where x+y+z=100 by weight, were melted and formed into a specimen of the size 2.5×5×50mm. They were heated from room temperature to 1200°C with the rate of 5°C/min. and then held there for two hours. Among the polycrystalline materials, the one produced from a glass of the composition of Li2O 4, MgO 15, Al2O323, SiO262 showed the highest modulus of rupture (1, 550kg/cm2).(2) Process of cristallization of the glass during heat treatment Thermal differential and X-ray analysis made with the glass specimen of above composition showed that, during its heat treatment, β-eucryptite was first precipitated at about 850°C and then β-spodumene at about 1000°C (Fig. 9). Microscopic examination showed that β-spodumene, after its precipitation, decreased its grain size by fission, by still unknown reason, with increasing temperature (Fig. 10, b, c, d). Above 1000°C the marked increase in specific density of the specimen with increasing temperature was also observed (Fig. 12).(3) Effects of heat treatments on strength The conditions of heat treatment such as the heating rate and the maximum holding temperature were varied and their effects on the modulus of rupture of the resultant polycrystalline materials were determined. The slow heating with the rate at least below 5°C/min. in the temperature interval of 800 to 900°C, in which β-eucryptite was first precipitated in the specimen, was found to be necessary increasing the strength (Fig. 6). The specimen which missed this heat treatment had poor strength (Fig. 5). The strength was also found to increase with increasing the maximum holding temperature (Fig. 7). This change was attributed to the decrease in grain size of β-spodumene and also to the compacting of microstructure.

This paper is divided into two major sections. The first of these describes the types of defects which may arise in crystalline materials. These may be classified as point, line, sheet and volume defects, examples of the four groups being vacancies, dislocations, grain boundaries and precipitates. The basic defects of crystal structures are first described, particular attention being paid to dislocation lines and the way in which a perfect dislocation may dissociate into two partial dislocations and a ribbon of stacking fault. The motion of defects, including glide, climb and cross-slip is discussed. This section ends with a summary of the ways in which basic defects may interact and combine, and be used to describe such microstructural features as deformation twins and precipitate boundaries. These defects form the basis of the mechanisms, given in the second part of the paper, which have been used to explain the various phenomena of hardening and fracture. No attempt has been made to give detailed theories of these mechanical properties. The treatment is intended for the nonspecialist, interested in obtaining an understanding of how a knowledge of the microstructure of materials may be applied to specific problems.

In this study, various chemical and electrographical methods were tested so that to determine porosity in the coatings on aluminium. Filter paper or desilvered photographic paper was used as the printing medium. Certain sensitive indicating reagent was dissolved in alcohol which contains, as electrolyte, a small quantity of NaCl dissolved in water. When the printing medium was pressed on the surface of a specimen, aluminium was preferentially dissolved. Aluminium ions were transfered through pores in the coating to the printing medium and reacted to form a colored product. It was found that aluminon and eriochromcyanine R were suitable agents for good printing.It was revealed by optical microscopy, that the porosity prints obtained by this method were closely relative to the microstructure of the surfaces. The method was also applied to the determination of porosity in the anodized films. Also was it known by the corrosion test that the corrosion spots found on the specimen printed by the method are relatively in parallel with the printed spots.

In this paper, the authors investigated the mechanisms of bending fatigue breakage of gears in one side and reverse loading conditions by examining the change in microstructure and in magnitude of residual stress with the number of load cycles and proposed Na-Np diagram, in which the number of load cycles after reverse Na is plotted against the number of load cycles before reverse Np, to indicate the bending fatigue properties of various gears such as annealed carbon steel gears, case-hardened gears etc. Moreover, the bending fatigue properties of shot-peened gears which had residual compressive stresses of considerable magnitude were investigated and it was made clear that there exists the optimum shot-peening conditions for the bending fatigue strength. The results obtained in this paper indicate some points which must be taken into consideration in the practical strength design of gears.

This is the second in a series of papers coming from this laboratory on the correlation of the low temperature tensile properties of tin-binary alloys with microstructure. These engineering data and those of the previous paper were obtained as the initial part of a long-range program to determine the changes in the fundamental mechanical properties accompanying the beta to alpha phase change in tin and its binary alloys below 13.2 deg C. Since it appears now that the more fundamental studies will be delayed, and since no summary of the low temperature properties of these tin-base white bearing alloys was found in the literature, it was decided to publish all the engineering data thus far obtained.

IN a recent paper Balluffi el al. I refer to the work of Bredt and Koehler e on the annealing behavior of copper deformed at subzero temperature. 99.999 pct pure Cu was deformed at -195~ and significant changes were reported to have been observed during holding at -195~ for long periods. The authors also make the important observation that such aging at -195~ could substantially alter the subsequent annealing at higher annealing temperatures. Essentially similar results were obtained on specimens of indium of >99.9 pct purity and the present paper describes briefly the important observations recorded. Specimens of indium were deformed in compression by 30 pct at liquid nitrogen temperature. The deformed specimens were then given two types of treatments. In treatment a, the specimen designated a, was rapidly brought up to room temperature, +20~ In treatment b, the specimen designated b, was kept at -193~ in a I liter dewar until the liquid nitrogen had evaporated over a period of 24 hr. At the end of this stage, the specimen temperature rose slowly to +20~ Specimen a, was metallographically prepared first. Specimen b was prepared after all the liquid nitrogen had evaporated and the specimen temperature reached 20~ Details of sample preparation and etching procedure have already been described in the literature, s After this stage, the specimens were kept in a dessicator at +20~ for 3 weeks, during which period they were examined metallographically at regular intervals. The above set of experiments, i .e., treatments a and b and aging of specimens a and b for 3 weeks at +20~ were repeated three times and the results reported below were found to be reproducible. The microstructure of specimens at the end of treatments a and b are shown in Figs. l(a) and (b). The structures are free of deformation traces and are fully recrystallized, being made up of a range of grain sizes. The presence of many annealing twins can also be seen clearly in the figures. Etch pits, faintly outlining some form of prior grain structure, e.g., Fig. l(b), were observed in both specimens and their significance will be discussed in the following section. The important differences between Figs. l(a) and (b) are as follows: Specimen a is made up predominant ly of ve ry coa r se g ra ins with only a few sma l l g ra ins . In spec i men b, there a re many more smal l g ra ins than in spec imen a and the average gra in size of the c o a r s e r g r a i n s appears to be s m a l l e r than in spec imen a. Both spec imens were examined at r egu la r i n t e r va l s dur ing the holding per iod. The m i c r o s t r u c t u r e of spec imen a r ema ined e s s e n t i a l l y s table , apar t f rom ce r t a i n minor changes to be desc r ibed la ter . However, s ignif icant changes in the m i c r o s t r u c t u r e of spec imen b were obse rved dur ing holding. Dis t inc t

Remendur alloys, one of which is used as the base material in remanent reed sealed contacts for the communications industry, are ternary alloys containing approximately equal iron and cobalt with 2 to 4 wt % vanadium. The available equilibrium diagram for this system does not provide precise positioning of the phase boundaries in the regions of commercial interest and, consequently, does not permit accurate determination of the amounts of the phases present or their compositions. This paper reports on the precise determination of five tie lines in theα 1+γ two-phase field in the region of interest, by metallographic and microprobe techniques. In the 900 to 950° C range, this field was found to be narrower than expected from published data. Submicron fcc (γ) particles form during annealing at 600° C by decomposition of a non-equilibrium bcc (α2) phase into a secondary ordered bcc phase (α′1) and stabilizedγ. Deformation, by drawing and by stamping, enhances coercivity in these alloys by promoting a more uniform, more finely divided dispersion ofγ particles. Annealed microstructures are especially sensitive to vanadium content, annealing temperature, and annealing time.

In relation to the production of composite materials, the present paper studied the influence of the solidification rate on the microstructure of an unidirectionally solidified eutectic Al-Fe alloy. The results obtained are as follows:(1) When the solidification rate was less than 10cm/hr, FeAl3 rods were regularly aligned parallel to the solidification direction. However, when the solidification rate was more then 20cm/hr, the microstructure became irregular, as observed in the normal cast structure.(2) The eutectic compounds under high and low solidification rate were rods and flakes in shape, respectively. It was found that the rod diameter decreased as the solidification rate increased.(3) The interrod spacing, λ, was related to the solidification rate, R, as λ2R=K, where K was 2.7×10-9cm3/sec.

In the previous report, the various factors that affect the endurance limit of induction hardened steel were examined. It was found that the microstrain and particle size are more influential than the residual stress on the endurance limit of both induction hardened smooth and notched specimens.The present paper describes an experimental study on induction hardened smooth specimens tempered at various temperatures to find out main factors affecting the tension and compression fatigue strength and changes of the integral width and structure during fatigue. The main results are as follows:(1) The compression and tension endurance limit decreases with rising tempering temperature. But the influence of tempering temperature on the compression and tension endurance limit is smaller than on the rotating bending and the plane bending.(2) A linear relation exists between integral width, or micro-strain of particle size obtained from profile analysis and endurance limit.(3) The integral width and microstructure of hardened material such as induction hardened steel change during fatigue, and the fatigue damage exists in a wide area.

The refractories made from dunite shows usually the complicated change of microstructure during the furnace campaign due to the change of temperature and atmosphere. This may lead to the complete collaps of the whole structure, and is the very reason which has checked its practical use.R. L. Stone and also Ikenoue suggest that the iron, existing in the state of solid solution in the mineral, would be the main source of the occurence of such damage. The author has carried out the investigations for the purpose of improving the instability by taking away the iron through the electric melting under reducing condition.The present paper concerns the observation of the author on the process of remove of iron and silica by the electromelting of dunite from Fukushima prefecture. Especially on the influence of the reducing agent (carbon powder and the powder of pig iron) on the structure of electro-molten dunite is discussed. It was confirmed that the size of forsterite crystals in the mass obtained by electric melting reduced their size with the increasing amount of the reducing agent.Above all it would be worthy of noted that the separation of periclase crystals was observed in the mass reduced by iron, and the probable existence of close relation between the compositions of the dust and the ingot obtained by electro-melting was also noticed.

It has been evidently observed by X-ray technique that the grains of aluminium or Al-Cu alloy is, at the begining of extrusion, disintegrated into many small domains with small difference in orientations.To determine these domains under microscope, several electrolytes were investigated and some favourable conditions were found.These conditions and polishing method for microstructural test are illustrated with photographs in this paper.

It has been understood that the fatigue strength of machined materials increases by the hardening work in surface layers. In these hardened surface layers, microstructures, such as dislocation structure, might be variable with the extent of working. And there might be variation in surface structure during the fatigue.Therefore, in order to clarify the surface structural changes during the fatigue of the annealed low carbon steels and the surface-rolled ones under three different working conditions, in this paper, the observations on the notched part of the rotating bending fatigue specimen are performed by light microscope and electron microscope with replicas, and the properties of slip line and fatigue crack initiation have been made clear.The summarized results are as follows:(1) The morphology of slip lines are variable from the annealed specimens to the surface-rolled specimens. In the former the fine slip lines are formed near the grain boundaries, and in the latter the slip bands are formed locally in the ferrite grains. These slip bands increase in length and width as the number of cycles increases.(2) The higher the rolling pressure rises, the more preferential slip bands are formed in the ferrite grains. The microcracks in the highly rolled specimens tend to initiate within the slip bands before these slip bands interfere each other.(3) Under the same cyclic stress condition, the time of emergence of the slip lines is earlier in the surface-rolled specimens, but that of microcracks is slower than that in the annealed specimens.(4) The direction of the slip lines in the surface-rolled specimens is perpendicular to the maximum tensile stress axis.(5) The slip ratio during fatigue increase more slowly in the surface-rolled specimens than in the annealed specimens.

Nakaya wrote a poem in which he says “Snowflake is a letter to us from the sky”. If expressed similarly, mineral crystals in nature are the letters to us from the depth of the earth. They convey the message telling us what has happened under the earth, what was the conditions when they were grown, and what they have experienced since they born. It is clearly worth doing our best to read these letters. As Nakaya tried to read the message that snowflakes convey by studying their crystal morphology, we can obtain much information through detailed studies of the nature of crystals. Surface microstructure of crystal faces, zonal structures inside a crystal, distribution of foreign crystals and lattice defects, as well as impurity atoms, in addition to crystal morphology, will serve as useful key codes to decode the letters.In this paper, diamond crystals are used as an example how to decode the letter from deep under the earth. Analysis of crystal morphology of diamond suggest that natural diamonds were grown under near-equilibrium conditions, whereas synthetic crystals under the conditions apart from the equilibrium. Universal occurrence of rounded crystals in natural diamonds suggests that they have experienced dissolution process while they were transported to the earth's surface from the depth, and that the speed of transportation was much higher than our general conjecture. It is also conjectured that diamond will occur only in continental shield and not in the orogenic zones. Observations on the surface microstructures of diamond crystals shows that diamonds were grown from solution phase by condensation and neither from melt phase nor by solid state recrystallization. Zonal structures revealed by chemical etching show that the growth of diamonds was carried out by layer spreading mainly on {111} and that the growth history of individual crystals was very complicated. During the whole history of growth, crystals have experienced partial dissolution, changes in growth speed as well as the rate of impurity adsorption. Recent observations on the nitrogen platelets in natural diamond crystals give an idea that diamond crystals have experienced annealing stage after they were formed, and that the possible origin of carbon of diamond would be carbonaceous material deposited on the ocean bed, which was then transported by an active thrust or heat flow to the depth of 5 to 7 hundreds km, where it was crystallized as diamond. These considerations are mainly based on the hypothesis on the origin of diamond which has recently been proposed by F. C. Frank.

Quenched beta-phase alloys in systems based on the noble metals are often thermodynamically metastable. A review of the information derived from transmission electron microscopy indicates the presence of various anomalous contrast and diffraction effects in such alloys. Contrast effects may be referred to as mottling, striation, cross-hatching, etc., and they may change in intensity with respect to different extinction contours, foil thickness and foil tilting. Diffraction effects refer to diffuse streaking in certain directions, the appearance of additional maxima or their splitting, and slight deviations from cubic symmetry. The possible causes for the presence of such features are discussed in the present paper. Some effects are considered to be at least in part the result of surface rippling, caused by electropolishing, but other effects are associated with the presence of precipitates, or with atomic displacements from ideal bcc packing. A detailed analysis of the diffraction effects suggests that structural features must be present analogous to the hexagonal ω-phase (known in transition alloys), and the nearly hexagonal α′ phase (known in bainitic structures). The stability of the beta-phase alloys is considered in terms of the above features, concluding that both vibrational and electronic entropy terms may be contributing, and that instability at low temperatures may be manifested in a number of ways not all of which fit into conventional phase-transformation categories.

The need for improved materials in high temperature structural applications has stimulated research into the mechanical behavior of a number of materials including the refractory hard metals. The transition metal carbides are of particular interest for a number of reasons, for example: (a) these compounds include the materials having the highest melting points, (b) they are extremely strong, and (c) they deform plastically in a manner similar to f.c.c. metals. The purpose of this paper is to review the present understanding—or lack of it—of the deformation process and the factors affecting the mechanical behavior of these technologically important materials. Consequently, the more interpretable information obtained in recent years from studies of single crystals, rather than that from sintered polycrystalline materials, is emphasized.

This paper describes an etchant, chromic acid, which reveals the microstructures present in bulk samples of annealed isotactic polypropylene. It is shown how this reagent may be used first, to follow the attack of fuming nitric acid on polypropylene, and second, to identify the types of crack which occur when a bulk sample of annealed polypropylene fractures under tensile load.

A method of etching high purity zinc to reveal various etch figures on {101¯0} planes is presented in this paper. Etch figures are formed by polishing in a dichromic acid solution after the introduction of mercury to the crystal surface. No measurable aging time is required to form etch figures at newly formed dislocation sites when mercury is on the surface prior to deformation. The mercury concentrates at the sites where etch figures form and may be removed by vacuum distillation and chemical polishing before it appreciably affects the purity of the bulk of the crystal.

Four series of bodies were fired with the schedules shown in Fig. 1. Soaking was done only on the rapid (180°C/hr) fired bodies. Translucency of the fired bodies were measured by means of photo cell, and the relationships between the translucency and the microstructure of which the details have been reported in the previous papers were discussed with the following results:(1) Translucency of the bodies increased abruptly within a very narrow range of firing temperatures, and also increased greatly within a short period of soaking.(2) The temperatures at which translucency of the bodies abruptly increased, lie, e.g., in the case of firing rate of 60°C per hr., at about 1225°C for potash feldspar, and at 1210°C for soda feldspar, and these strictly coincide respectively with the temperatures at which dissolving of the feldspars progress suddenly.(3) Translucency of the bodies containing soda feldspar increased abruptly at lower temperatures than in the case of the bodies containing potash feldspar while, above these temperatures, translucency of the latter become markedly greater than that of the former. Causes of these inferiority of translucency of the bodies containing soda feldspar are inferred as follows:a) Soda feldspar usually comprises a solid solution of plagiociase having so large composition range, that its melting is continued up to the comparatively high temperatures.b) Viscosity of the soda feldspathic melt is lower than that of potash feldspathic one.c) Owing to these two reasons mentioned above, homogeneity of glasses formed in soda feldspathic bodies is largely inferior to that of potash feldspathic ones.d) Bubbles contained in soda feldspathic glasses are smaller and more abundant than in the case of potash feldspathic ones.(4) Addition of coarse grained quartz into feldspathic body, even if a few per cent, will result in a marked decrease of the translucency of the body, if the body will not be soaked at all. With increasing content of fine grained quartz, translucency of the body will also decrease, though not remarkable.(5) So far as the translucency of the body of the present system is concerned, soaking time is one of the most important factors.(6) It is confirmed again that the unhomogenity of optical density of glasses formed in the body is one of the most important factors affecting the translucency of the body, as has been reported in the previous gaper.

This paper purports to inrestigate the effect of irradiation by Co-60 on the fundamental characteristics, weldability and adhesiveness of polyethylene.High pressure polyethylene films, 0.07 mm in thickness, were used in this experiment and exposed to various irradiation doses up to 5×107r under various ambient conditions. Measurements of degree of crystallization, resolution rate in xylene, wettability and others were made. These materials were welded with heated tool or bonded by various adhesives and then experiments on boniing strength were performed.The results are summarized as follows:Decay of crystal and change of degree of crystallization about irradiated polyethylene were not recognized within the ilmits of this experiment. It can be concluded that the increase of cross linkings due to irradiation makes weldability lower and carbonyl groups whose existences have been confirmed by infrared spectra analysis imdrove adhesiveness.

The characteristics of the deformation and fracture of metals under repeated cycles of stress, generally described as “fatigue phenomena,” have received very considerable attention, both experimental and theoretical. Usually, consideration has been devoted exclusively to conditions in which the metal subjected to fatigue has its free surface exposed to the ordinary atmosphere. In many cases in actual practice, however, metals are subjected to fatigue action while surrounded by a fluid—either gaseous or liquid—which is of a corrosive nature and the endurance or “life” of the metal is controlled by the simultaneous conjoint action of the applied stresses and the corrosive agent. To such conditions the term “corrosion-fatigue” has been applied. Attention was first directed to this aspect of fatigue phenomena in 1917 by Haigh, who demonstrated experimentally that, in general, fatigue stresses and corrosive influences may be mutually accelerative, producing more destructive effects than either influence when acting separately, or when the stressing is applied subsequent to the corrosion stage. The subject then appeared to escape further attention for a period of about nine years, after which the results of the first of a series of important researches were published; in this connection reference should be made to the work of Lehmann, McAdam, Speller, McCorkle and Mumma, Binnie, Fuller, Haigh and Jones, etc. From the researches of these investigators, and particularly from those of McAdam, a very large amount of data is now available regarding the corrosion-fatigue resistance of a wide range of metals and alloys, and the separate effects of such variables as frequency of stress cycle, number of cycles, corrosion time, applied range of stress, etc., also of corrosion inhibitors and accelerators. No attention has apparently been given hitherto to the changes in microstructure occurring during a corrosion-fatigue test and, as a result, no information existed on such fundamental points as (i) the general course of a corrosion-fatigue crack; whether intercrystalline or transcrystalline; (ii) the actual point of initiation of the crack; whether it is situated at a crystal boundary, or on the site of previous slip bands, or at local corrosion pits bearing no distinct relation to these special positions. In planning a research with these general objects in view it was decided to make experiments, under corrosion-fatigue conditions, on ( a ) a single crystal, ( b ) a specimen consisting of two large crystals with the separating boundary, and ( c ) a specimen consisting of the usual finely-divided aggregate of crystals. By using single crystals and large crystal specimens and employing X-ray, microscopical and mechanical methods, it was hoped to correlate corrosion-fatigue phenomena with the fine structure. The present report describes the observations made on what is believed to be the first corrosion-fatigue test on a single crystal.

The preparation of graphites has been worked by pyrolysis of propane gas on a directly heated substrate in the vapor phase stirred by a fan. Its formation process and structural features (microstructure, density, and crystal structure) were examined on several samples deposited under various conditions at deposition temperatures of 1440, 1730, 2025°C, gas pressures of 10, 25, 50mmHg, and gas flow rate of 640cm3/min. The effect of stirring vapor phase is appreciable at high temperatures and high pressures. The convection of the decomposed gases or gaseous products disappears in the stirred vapor phase. It follows that the abnormal behavior observed in the pressure range of 20∼30mmHg as described in a previous paper is restored to its normal behavior. The formation process in the stirred vapor phase is discussed in relation to the change in the structural features under the gas pressure.

This paper analyses the symmetrical bending of laterally loaded circular micropolar plates. The linear theory of micropolar plates has been used to investigate the effect of microstructure of the medium on bending of circular micropolar plates. It is found that the results of the new plate theory are dependent on Poisson's ratio and two new parameters which are related to the material constants of the micropolar plate theory.

The advantages of a systematic application of the method of virtual power are exemplified by the study of continuous media with microstructure. Results on micromorphic media of order one are easily found and the equations of motion for the general micromorphic medium are established for the first time. Various interesting special cases, which have been previously considered in the literature, may be derived upon imposing some convenient constraints. The paper ends with some comparisons with other related work.

Thin-film deposition techniques as applied to magnetic memory applications are reviewed. The relationship between the microstructure of the film and the fabrication technique and pertinent parameters is discussed in terms of the atomistics of film nucleation and growth. The dependence of the magnetic properties governing switching of a magnetic storage element is qualitatively discussed in terms of the microstructure and ripple theory; literature data is used to elucidate this by showing the effects of composition, temperature, thickness, and substrate morphology on the magnetic properties. The literature values for the anisotropy field, coercivity field, and dispersion of various classes of ternary alloys is reviewed, extending previous papers reviewing elemental and binary alloys.

Creep, shrinkage and delayed thermal dilatations of concrete have source mainly in the interaction with water of the internal surfaces of solids in the cement paste microstructure. This interaction is believed to consist in changes of thickness or mass content of mono- and multimolecular adsorbed water layers confined between two solid adsorbent surfaces. These changes are brought by diffusion of water and other molecules along the layers. In the present paper a consistent formulation of the above mechanism based on surface thermodynamics is presented and the isotropic macroscopic stress-strain relations are derived. These relations indicate the form of the dependence of material parameters on pore humidity and temperature, and restrict considerably the number of possible forms of constitutive equation that would have to be assumed on a purely phenomenological basis if the material were regarded as general interacting continua in which strains are general functionals of the history of water content and temperature. A viscoelastic material with time-dependent properties is obtained as the special case for constant humidity and temperature. A suitable, numerically stable algorithm of step-by-step time integration of stress and strain problems is also presented. Analysis of experimental data aimed at numerical determination of the material parameters is presently in progress at Northwestern University.

As a basic study of brazing, two dissimilar metals in contact with each other were heated to a specified temperature and fused in an electric furnace, then the micrographic structure of the bonded layer was studied to establish the relation between the microstructure of the layer and the heating temperature.As the simplest case, this paper is concerned with the microstructure of the combination of pure metals which form eutectics. The microstructure of bonded layer was determined by X-ray microanalyser and X-ray diffractometer.Six combinations (Bi-Cd, Bi-Sn, Ti-Cu, Ti-Co, Ti-Ni and Zr-Ni) were treated as the specimen, each combination being examined individually. The following results were obtained:i) The temperature for producing the molten layer must be, at least, over the lowest (or the first) eutectic temperature on the equilibrium diagram, and the composition of the molten layer agrees with that of eutectic point (see photo. 1, 4, 8, 13).ii) When the temperature rises further and attains the upper (or second) eutectic point for instance a eutectic temperature, 1135°C, 82 wt% Co system such as the case of Ti-CO system, in the case of Ti-Cu and Zr-Ni, the second eutectic structure co-exists with the first eutectic structure depending on the speed of its producing process (see photo. 6, 14). However, in the case of Ti-Co and Ti-Ni, the whole specimen melts by heat which is produced by metallic compound formation constituting its eutectic structure (see photo. 9, 11).

The X-ray flaw detection of austenitic stainless steel welds has been complicated by abnormal beam transmission. This phenomenon is often detected as a linear faint contrast in a radiograph which easily produces a misleading image corresponding to incomplete penetration of welds.This paper accounts for this contrast due to diffraction of X-rays transmitting through the welded zone where the anstenite crystals exhibit pronounced preferred orientation, as called columnar structure.Several evidences of diffration contrast in continuous X-rays are obtained, and it is concluded that, in general, microstructures such as coarse crystals or preferred orientations in metals are expected to have influence on the X-ray radiograph.

In succession to the investigation on the crystallization of mullite needles in large feldspar particles this paper concerns on the microstructure of the bodies consisting of coarse feldspar grains embedded in kaolinite powder.Complicated Becke's lines were observed at the boundary between the molten feldspar grain and the matrix phase suggesting that there was diffusion between the two phases.The photomicrograph (photo 2) indicates that the molten feldspar showed the trend of approaching each other by forming the veins in the matrix, or by the deformation of the grains.During these processes the pores included in the grains joined together to become larger (photo 2, 3). At higher temperatures the reduction of viscosity made the reaction more and more rapid until the bubbles suddenly open. This may be a mechanism of the formation of bubbling in over-fired bodies.Feldspar grains locating next to cracks indicate that the molten mass pushed into the cracks through the veins by the pressure of expansion of feldspar with melting and pores in the grains.It was thus observed that the pores near the cracks are larger than ordinary size, suggesting that the bubbles in the molten feldspar had the potential power of further expansion puhsing out the matrix, changing the shape of the grains to promote the intrusion of molten feldspar through the veins.If the body was heated further after the cracks had closed the expanding gases found their way in the weak points to form large pores in the feldspar grains locating near the cracks. It is highly probable that a part of pores in porcelain bodies were formed in this way.The needle crystals came out earlier and far greater in number in feldspar melts being sandwiched in the crack.In a few specimens fired at as high as 1450°C it was observed that the needle crystals were concentrating at the surface of large bubbles showing that they were pushed back by expanding gases after the deposition of the crystals. It was also observed that the crystals were accumlating at the surface which was pushed back by expanding gases enclosed in the crack. This is the positive proof of the author's conclusion that the needle crystals in feldspar appears in the heating up period.Moreover, it was concluded that the deposition of the crystals in molten feldspar begins in the heating up period when the expansion of gases and the penetration of feldspar into the crack have just come to an end.

The present paper is primarily a study of the ordering characteristics within the CuPt system, near the CuPt composition, using X-ray diffraction, optical microscopy (in conjunction with polarized light), high-voltage electron microscopy and dilatometry. In platinum-rich off-stoichiometric alloys, a wide two-phase region consisting of ordered + disordered platelets was established and the phase boundaries were accurately located. For isothermally ordered stoichiometric alloys, in general two categories of diffraction sequences were observed, depending on the annealing temperature. For anneals in the range 620°C

It is very important that the behavior of structurals will be studied under repeated impact loads, but there have been few papers hitherto published about impact fatigue since few efficient impact fatigue testing machines have been made available.So, we devised a new rotating disk type impact fatigue testing machine, of which the impact velocity and the number of impacts per minute were 5.5m/sec and 600 respectively, and studied the effects of microstructure on the impact fatigue lives.The 0.24% carbon steels, and 0.85% carbon steels with lamellar and spheroidal pearlite structure were used, of which some were annealed while others were left as they were when obtained.The results obtained are as follows.(1) The impact fatigue lives of 0.24% carbon steels were longer than those of 0.85% carbon steels, and the slopes of S-N curves of the former were steeper than those of the latter.(2) The impact fatigue life of the annealed 0.24% carbon steel was longer than that of the 0.24% carbon steel that was left as it was.(3) The impact fatigue life of 0.85% carbon steel with lamellar pearlite structure was almost the same as that of 0.85% carbon steel with spheroidal pearlite structure.

It is quite well known that a remarkable rise of fatigue strength of an induction-hardened, carbon steel specimen, can be attributed to the following : 1) Quenching after rapid heating may improve the mechanical properties of material. 2) The existence of residual compressive stress in the surface layer of the specimen may prevent the fatigue crack from propagating. However, it has not been clarified which of these has a more important bearing on the fatigue behavior of induction-hardened steel. In this paper, the mechanical behavior of retained ferrite was investigated, which was considered to govern the fatigue behavior of induction-hardened steel being free from the residual stress. Results obtained are as follows : the fatigue crack originates in the part of the retained ferrite in the quenched microstructures, and the final fracture seems to be governed by the surrounding quenched microstructures.

This paper presents work relating heat treatment, microstructure and fracture mode with KIC and COD for a quenched and tempered En 24 steel. Specimens were taken from three different blooms representing the top, middle and bottom of an ingot and given a number of heat treatments designed to produce a range of prior austenitic grain sizes and a range of tempered microstructures. The results show that variation of the tempering temperature has virtually no effect on the toughness. 45 MN/m 3 2 , until temperatures above 350°C are reached. There is a steep rise in toughness to around 80 MN/m 3 2 as the tempering temperature is increased to 450°C. Reduction m prior austenite grain size from ASTM 5–6 to ASTM 12–13 also leads to a significant increase in toughness (from 44 to 82 MN/m 3 2 ). So far as ingot position was concerned there was no difference in the toughness of material taken from the top, middle or bottom. There was however, a small but significant (3.5 MN/m 3 2 ) difference in toughness between material taken from the inside and outside of blooms; the inside material was tougher, perhaps because there were fewer but larger inclusions in the core of the ingot. Attempts to correlate toughness values with other microstructural features were unsuccessful. There was reasonably good correlation between the toughness as measured by critical stress intensity factor KIC and by the plastic component of the critical crack opening displacement COD. As a method of toughness measurement on these steels COD is of limited value because the greater part of the COD as measured is attributable to the elastic deformation of the test pieces.

Compositions in the tantalum-carbon system were prepared by carburizing high-purity tantalum wires. The microstructures so produced exhibit regions of a characteristic striated structure identical to those observed by earlier investigators. There are disparities in the literature as to the origin of such structures in the tantalum—carbon system. They have been variously described as “twins,” “striated structure,” “precipitate,” and “structure of unknown origin.” This paper presents conclusive evidence that the structures in question are the result of precipitation on cooling. In addition, a coherent precipitation model is applied in which it is shown that the lattice relationship {0001}Ta2C‖{Klll}TaC can exist with less than 0.5% misfit. This relationship is shown to completely explain the occurrence and characteristic appearance of the observed micro structures. Correlations between chemical analysis, X-ray diffraction results, metallography, and microhardness measurements confirm the proposed precipitation model.

One of the authors has previously published the detailed procedures for plate bending by Line Heating Method, and showed its great promises for bending the steel ship hull plates. This method, which is consisted of heating and subsequently water-cooling a steel plate, has been suspected by not few concerned as possessing harmful effects on material properties. However, it was then proved by various tests such as static-tension, bending, V-notch Charpy and hardness tests or microstructure inspection, that the effect on material is as slight as that caused by press-bending in, either cold or hot state, because the heating in this process is duly controlled so as not to heat the plate beyond A-1 transformation point of steel.Recently, a number of large-scale brittle fracture tests, which is believed to have good correlation with brittle fracture of actual steel structures, has been developed. A Double-Tension test is one of the most representative of these large-scale tests, and the brittle-fracture properties of steel plates bent by Line Heating Method was investigated with this test by the present authors, the resultls of which are reported in this paper. It was revealed that the heated zone of steel plates becomes indeed more brittle than the original material, but the degree of deterioration is almost same as that caused by press-bending ; in other words, Line Heating Method can safely be used for ship hull steel plates from the viewpoint of brittle fracture.It was also found that the shear-fracture transition-temperature by Pressed-notch Charpy test is 'highly correlated with the arresting-temperature obtained by the Double-Tension test, if the applied stress is nearly as high as the yield point of the material.

In the previous papers, the diffusivity of hydrogen in steel could be explained comparatively well by using the Fick's second law, assuming that steel was homogeneous on the whole.In this report, using the steel specimens varied in structures, the effects of the structures on the diffusion coefficient of hydrogen were described.The experimental data which were obtained from the permeability tests were analyzed by using the Time Lag method, and from its analysis, the diffusion coefficients of hydrogen in some structures of steel were calculated.The results obtained are as follows;(1) The hydrogen diffusivity depends upon the structure of steel. The ferrite+pearlitc structure has a large diffusivity, and the martensite has a small one. This tendency of the hydrogen diffusivity well agrees with the results from the hydrogen occlusion test.(2) The solubility of hydrogen in each structure is respectively 40cc/100gFe (ferrite+pearlite), 26cc/100gFe(troostite) and 24cc/100gFe (martensite). These values are consistent with the results from the hydrogen occlusion test.

This paper presents the effects of various small alloy additions on the mechanical properties and microstructure of hot-worked, silicon-killed SAE 1020, steel.

In this paper the mcehanical properties of five series of cast specimens, simulated to weld metal in cooling rate, were examined to investigate suitable chemical compositions of weld metals of enough strength and ductility by Subzero welding process. These cast specimens of high alloy Ni-Cr steels with unstable austenitic microstructure were tested as cast, refrigerated at -72°C in collant of methylalcohol and liquid nitrodgen or aged at 45°C after refrigeration. The results were as follows;1. In Cr-Ni-2 %Mo(0.05%C)series, 0.2%proof stress of cast specimens were increased by refrigeration, but elongations of them were decreased. However both 0.2%proof stress and elongation were increased by aging.2. In l4%Cr-Ni-2%Mo-(3_9%)Mn (0.04%C)series, by increasing manganese content instead of nickel content elongations and Charpy impact values of cast specimens were increased, but incre-ments of strength of them by refrigeration were decreased comparably.3. In 14%Cr-9%Ni-(Mo, Cu, Co, or Ti) series, 0.2%proof stress of cast specimens were increased by adding alloying elements, Elongations of them by refrigeration were larger than that of other series cast specimens.

This paper deals with the effect of preparation parameter on particle size and microstructure of the prepared ferrosoferric oxide. 10 prepared samples (from 23 samples) and one standard sample (Bayferrox 318 standard 88) collected from BAYER, Germany was selected for this study. X-ray diffraction, petrographic microscopy, scanning electron microscope and particle size analyzer were used to characterize the phase present, particle size and shape of the particle. It is observed from X-ray diffraction that all these samples mainly contain Fe3O4 phase. The shape of the particle is found to be round and agglomerated. The average particle diameter of highest portion of pigment in the peak region is ranged from 12.25μ to 17.32μ, which is very similar to the standard sample (17.32μ). Sample number 9, which was prepared with ferrous sulphate, hydrochloric acid, sodium nitrate and ammonium hydroxide at a molar ratio 1:1.74:0.16:4.07 and standard sample contain narrow high peak in their particle size distribution curve. Another observation is that, experimental parameter, though have some effect on particle size but have no effect on microstructure. Key words: Black iron oxide, Pigment, Particle size, Microstructure, Ferrosoferric oxide. doi: 10.3329/bjsir.v44i1.2711 Bangladesh J. Sci. Ind. Res. 44(1), 31-40, 2009

The microstructure of the shell of bivalve molluscs was examined by lightand electron-microscopy. The purpose of this paper is to classify and describe this structure, and to discuss the affinity and evolutionary development among different kinds of shells. Shell structure consists of two elements, namely, the morphological type which is divisible into 11 different kinds, and “growth line”. The distribution of each morphological type in pclecypods is summarized. Various combinations of morphological types are divided into four major groups. The origin of these types and groups is discussed.