Crystalline solid solutions between GaAs and GaP compounds were prepared from the melt under controlled vapour pressures. The experimental results were found to agree with the theoretical formulae derived in order to calculate the pseudo-equilibrium in a heterogeneous system consisting of two parts with different temperatures. It was assumed that all condensed phases would be regular or sub-regular and that the gas phase is ideal. In addition, some of the thermodynamic properties of the Ga-As-P ternary system were discussed. It was found that one can apply the concept of pseudo-equilibrium to the preparation of crystalline solid solutions of III-V compounds containing two volatile components.
Non-isoaxial bicrystals and their component single crystals of 99.99 wt% aluminium were investigated by the tensile test. The yield stress (ε=0.2%) and the hardening rate in the easy glide region were examined in reference to the misorientation and Young’s modulus between the component crystals. In about one-half of the specimens, the yield stress of the bicrystals was smaller than that of the component single crystals. It is shown that the grain boundary of the non-isoaxial bicrystal may promote the deformation in a certain condition, where the misorientation between the preferred slip systems of two component crystals in the vicinity of the grain boundary was small. The difference in Young’s modulus between the two component crystals was not a major factor for lowering the yield stress of the bicrystals below those of the two component single crystals. It was observed that the slip systems having the highest Schmid’s factor were not always preferred in the vicinity of the grain boundary, but those having Schmid’s factor above 0.40 and small misorientation were preferred.
The resistivity of the oxide film against pitting corrosion, the probability of occurrence of the anodic reaction at grain boundaries, cracks of the oxide film and the pitting corrosion on the surface from which the oxide film was removed by the cathodic reduction in the neutral solution or by the dissolution in the acid solution were investigated in order to make clear why a large number of pits are formed on the 18Cr-8Ni stainless steel oxidized at high temperature. The following results were obtained: (1) Pits in 18Cr-8Ni stainless steel oxidized in air at high temperature increase according to N=316(t+1⁄1000)1⁄2 where N is the number of pits and t the time for oxidation. As the above relation represents a parabolic law, i.e., X=K·t+K′, on oxidation, it is considered that the increase in the number of pits is caused by some sort of phenomenon which occurs in the process of growth of the oxide film. (2) The pitting potential series in boric-borax-2 mol/L NaCl solution of the specimens oxidized by various treatments is arranged in the decreasing order of resistivity against pitting corrosion: +0.83 V of 250°C×25 hr in pure water>+0.65 V of electropolishing>+0.64 V of 150°C×1.5 hr in air>+0.34 V of 250°C×1.5 hr in air>+0.14 V of 350°C×1.5 hr in air>+0.02 V of abrasion with emery paper. (3) The number of pits considerably decreases in the specimens from which the oxide film has been removed by the cathodic reduction in the neutral solution or by dissolution in the acid solution. Therefore, it is considered that the increase in the number of pits in the specimens oxidized at high temperature is caused not by defects of the matrix such as precipitation but by defects of the oxide film. (4) When the oxidized specimens are reduced cathodically, the reductive reaction of the oxide film occurs most preferentially at grain boundaries and cracks of the oxide film. Especially the grain boundaries are active sites and it is considered that both anodic and cathodic reactions occur easily at them.
The development of the direct and selective leaching method of metal sulfide is one of the most important subjects in the field of hydrometallurgy of sulfide concentrates and complex sulfides (Kurokou), etc. This study was done to find a clue to make clear the hydrometallurgical oxidation mechanism of ZnS in the aqueous solution of sulfuric acid. The effect of additions of CuS and PbO2, etc. to ZnS was discussed in terms of the stable potential, the spontaneous electrode potential and the results of the leaching experiment. The experimental results obtained are as follows: (1) The main dissolution reaction of ZnS in the acid solution is a type of H2S evolution. (2) The dissolution of ZnS is accelerated and the elemental sulfur is produced by the galvanic reciprocal reaction when CuS, PbO2 or graphite is added to ZnS. (3) As these additive elements have a higher potential than ZnS and have good electric conductivity, the following reaction is partly or wholly incorporated in the dissolution of ZnS. (This article is not displayable. Please see full text pdf.)
To clarify the effects of both grain size and carbon content on the ductility of molybdenum, the variations in ductility with grain size were investigated on the three grades of 1 mmφ wire specimens by means of tensile tests at 25° and −76°C, respectively. These specimens differed in carbon contents as \
otatebox[origin=c]180\gtrsim10 ppm, 80 ppm and 210 ppm. Oxygen and nitrogen contents were essentially of the same order for all of the specimens. The results are as follows: (1) Specimens containing \
otatebox[origin=c]180\gtrsim10 ppm carbon were extremely low in ductility due to intergranular brittleness when the average grain diameter in the transverse cross section was larger than about 0.04 mm, though they showed large ductility when it was smaller than 0.04 mm. In the fine grained specimens, however, the effect of grain size, per se, was obscured because the recrystallized grains were greatly elongated in the direction of the specimen axis and because an abnormal increase in yield stress was observed. (2) At −76°C, the ductility of specimens containing 80 ppm carbon increased with increasing grain size when the average grain diameter was larger than about 0.08 mm. (3) In specimens containing 210 ppm carbon the ductility increased nearly linearly with increasing inverse square root of the average grain diameter. In these specimens, however, the size of grain boundary carbides and the distribution of carbides in matrices also varied with grain size. (4) When the average grain diameter in transverse cross section was larger than about 0.04 mm, both of the specimens containing 80 ppm and 210 ppm carbon were clearly more ductile than the specimens containing \
otatebox[origin=c]180\gtrsim10 ppm carbon; which indicates that a suitable amount of carbon suppresses the intergranular brittleness and increases the ductility. Since coarse carbides, however, act as fracture initiation sites, the specimens containing 80 ppm carbon which were free from the intergranular brittleness but did not contain coarse carbides, were most ductile. (5) When the average grain diameter in transverse cross section was smaller than about 0.04 mm, the ductility of the specimens containing \
otatebox[origin=c]180\gtrsim10 ppm carbon was as large as, or slightly larger than, that of the specimens containing 210 ppm carbon. However, considering the uniaxed recrystallized structures in the former, it was not clear whether carbon increases or lowers the ductility in an equiaxed fine grained molybdenum.
This study was made to scrutinize the influence or effect on the wear resistance by a sulphurized layer which produces on the outer surface of cast iron subjected to sulphurization. A piece of spheroidal graphite cast iron used as a stator was treated in a reducing salt bath containing 5%Na2S2O3, and the reaction products produced on the outer surface was observed by X-ray diffraction. It was noticed that in addition to FeS, Fe1−xS and Fe3S4, carbides and nitrides such as Fe3C, Fe2N and Fe3N coexisted with α-Fe on the sulphurized layer of cast iron treated by a normal salt bath. Whereas, when cast iron had been treated with an inferior bath, porous and brittle reaction products consisting of FeS and Fe3O4 appeared around the outer surface, and in the underlayer the reaction products similar to those mentioned above were detected. The study was further conducted on a dry-sliding wear of these two kinds of sulphurized cast iron in connection with a rotor of S 45 C. As a result, it was recognized that sulphurized iron revealed excellent wear resistance in the compositional range where the adhesive or thermal wear appeared. It seems that such a phenomenon was due to the existence of a sulphurized layer which suppressed adhesion and welding between the stator and rotor, and also due to the said sulphurized layer which tended to produce an oxidized wear under a wide range of wear condition. In the cast iron treated with an inferior bath, there appeared heterogeneous reaction products on its outer surface as mentioned above, and the wear loss was comparatively great until the reaction products were removed from the surface. When the products were removed, a normal sulphurized layer came to appear on the surface, rapidly improving the wear resistance of cast iron. It has been made clear that the above observations coincide well with the distribution of sulpheric constituents on the sliding face examined by an X-ray microanalyzer.
Measurements of deformation and internal friction, and microscopic observations were carried out on annealed OFHC copper specimens when they were under various uniaxially repeated tensile loads. The results obtained were summarized as follows. The relation between amplitude and the repeated number to failure was nearly identical with the S-N Curve in the ordinary push-pull fatigue test. The ductile fracture occurred under the condition of higher stresses than 13.7 kg/mm2, and its fracture strain attained about 50∼60%. On the contrary, the fracture strain under the condition of lower stresses attained about 12∼15%. Local contraction could not be observed under the condition of lower stresses. Amplitude-independent internal friction which increased at the early stage of loading decreased monotonically with the increase of total plastic strain and then the internal friction increased again before failure by repeated loading. Persistent slip bands were produced under the lower-stress condition and microcracks to be characterized by fatigue failure also appeared along those slip bands. Development of cell structure under the condition of lower stresses was observed in a lower plastic strain region than that under the condition of higher stresses. These structural changes different from those produced in the structure under the condition of higher stresses or the tensile test. The changes in internal friction gave good agreement with that of the substructure of dislocations.
The effects of sulphur on the (110) secondary recrystallization in 70% cold-rolled Si-Fe alloy sheets were studied with an optical microscope and an electron probe microanalyzer. On annealing at 850°C, the colonies of fine grains with the (110) orientation were formed within a region of (111)〈112〉 deformed matrix. Raising temperature up to 960°C, some of the (110) grains were coarsened in these colonies of fine (110) grains by the migration of small-angle boundaries. On the other hand, the migration of high-angle boundaries was not observed during this process. Above 980°C, coarsened (110) grains grew abnormally consuming adjacent grains which had a large orientation difference from the former. By electron probe microanalysis, much sulphur was found at high-angle boundaries with a small radius of curvature. It may be explained that during the growth of (110) grains with small-angle boundaries, the migration of high-angle ones has been inhibited by sulphide. Moreover, at a higher temperature, the high-angle boundaries could move by dissociation of sulphide. The accumulation of sulphide along grain boundaries, which exerts a drag force on the migration of high-angle boundaries in the primary recrystallization structure and leads to the secondary recrystallization, would depend mainly on the misfit angle and some other factors relating to it. For these factors, the staying time, migration velocity of boundaries and the area swept by the boundaries should be considered. The contribution of coincidence boundaries to the formation of the (110) texture was also discussed.
Investigation was made on the effect of tempering temperature on the mechanical properties of carbon steel, Mn steel, Cr steel and Cr-Mo steel which had been forge-quenched. The results obtained were as follows: (1) The temper brittleness of forge-quenched Mn steel, Cr steel and Cr-Mo steel was more clearly observed than normally quenched steels when the specimens were tempered in the temperature range of 300°∼400°C or 500°∼600°C. From the Load-Time Diagrams of Charpy impact tests, it could be deduced that the increase in brittleness of 300°∼400°C tempered specimens was caused by the reduction in the maximum loads (fracture resistance), and that of 500°∼600°C tempered specimens was due to the reduction in time to fracture (deformation to fracture). The increase in temper brittleness was not observed with forge-quenched plain carbon steel. (2) When the specimens either normally quenched or forge-quenched were subsequently tempered at 350°C for 50 hr, there was observed no distinct difference in the structures of carbides and the matrix between these differently quenched specimens of the steels studied. However, when they were subjected to the tempering at 550°C for 50 hr, the carbides of forge-quenched steels were more needle-like than those normally quenched, and more lath-shaped martensites were retained in the matrix. (3) Comparison of impact strengths was made with those steels which had almost the same hardness but quenched and tempered in different ways. As for the specimens harder than Hv 300, the impact value of the normally quenched steel was higher than the forge-quenched or high-temperature quenched steel. As for the specimens of less than Hv 300, the impact strength became lower in the order of the forge-quenched, normally quenched and high-temperature quenched steels.
The influences of manganese, silicon, chromium and nickel on the solubility of niobium nitride in iron austenite have been studied by the method in which iron austenite was equilibrated with nitrogen gas. Manganese and chromium contained in iron austenite increase the solubility of NbN. Especially, the effect of chromium is more remarkable. On the contrary, silicon decreases the solubility of NbN. Nickel, in lower content, increases the solubility of NbN, but in much higher content, decreases it contrarily. The effects of those elements are more remarkable with decrease of temperature. Such effects are attributed to the effect of each element on the activity of nibium as well as that of nitrogen. Solubility product of NbN in iron austenite containing manganese, silicon, chromium or nickel is described by the following experimental equation, respectively: (This article is not displayable. Please see full text pdf.)
Annealed tough pitch copper containing Cu2O inclusion particles has been pressurized under various pressures up to 15000 kg/cm2 at room temperature and the dislocation structure formed by pressurizing has been studied by means of transmission electron microscopy. The results obtained are as follows: (1) The critical pressure required to nucleate and to form tangled dislocations around a Cu2O particle depends strongly on its diameter. The relation between the critical pressure and the particle diameter agrees well with the theory of Ashby et al. (2) The tangled dislocations show regular structures whose shape changes with the orientation of the foil specimen. This phenomenon is successfully explained by a mechanism of tangle formation through interaction and reaction between the dislocations generated on the surface of an inclusion particle. (3) The maximum range D of the dislocation tangle is proportional to the diameter of the inclusion particle d and increases with increasing pressure. The value of the ratio D⁄d is about 3 at 5000 kg/cm2 and about 7 at 15000 kg/cm2. (4) The dislocation tangles thus formed around the inclusion particles act as obstacles against the motion of dislocations when a pressurized specimen is deformed and cause the change of its mechanical properties.
The effect of pressurizing on the flow stress of copper up to 15000 kg/cm2 has been studied by tensile testing at atmospheric pressure and room temperature on polycrystalline specimens of two kinds of tough pitch copper (O2: 0.06 wt% and 0.03 wt%), low oxygen copper (O2: 0.004 wt%) and OFHC copper which contain various amounts of impurity oxygen. The results obtained are as follows: (1) For OFHC copper no change in the stress-strain relation is observed after pressurizing up to 15000 kg/cm2. (2) For the other materials which contain oxygen, pressurizing increases their flow stress at atmospheric pressure. There exist critical pressures, below which no effect of pressurizing is observed. The critical pressure for the low oxygen copper is higher than that for tough pitch copper. (3) The amount of the pressurizing effect increases with increasing oxygen content and pressure. (4) The increase of flow stress is very large at the beginning of deformation, but it decreases rapidly with increasing strain and becomes almost zero at large strains. (5) The above experimental results are explained by the following mechanism: The copper which contains oxygen shows a large amount of spherical inclusions of Cu2O. Hydrostatic pressure generates shear stress components around the inclusions and plastic deformation is induced at pressures higher than the critical pressure. Consequently, the work-hardened regions are formed around the inclusions and act as obstacles against the motion of dislocations resulting in the increase in yield stress and flow stress.
For the purpose of obtaining more detailed information on the phase transformation of metastable beta-type titanium alloys, the phase changes of Ti-Fe, Ti-Cr, Ti-Mn and Ti-Mo binary alloys during isothermal transformation were investigated by means of the microscopic observation and X-ray diffraction. The results obtained are summarized as follows: (1) Before the precipitation of the alpha phase, an unusual microstructure was observed in the specimens which were held for a short time at a given higher temperature prior to quenching. This unusual microstructure seemed to be caused by subgrain boundaries, etch pits and titanium hydride. (2) In the TTT diagrams obtained it was found that the starts of the beta-to-alpha and the beta-to-omega reactions shifted towards longer time and lower temperature as the solute concentration increased. (3) In each alloy system, the beta-to-alpha and the beta-to-omega transformations were observed. However, the beta-to-low concentration beta transformation below about 300°∼250°C, reported by Harmon et al.(17), was not observed. (4) In the specimens isothermally transformed above about 600°C the alpha phase precipitated predominantly at the grain boundaries, while in the specimens transformed below about 550°C the alpha phase precipitated in the grains. (5) Looking through the TTT diagrams of the alloys which have an equal atomic concentration, it was found that the rate of precipitation decreased in the order of Ti-Cr, Ti-Fe, Ti-Mn and Ti-Mo alloys. This did not coincide with the order of diffusion rate in the beta-titanium(18). In the case of eutectoid type alloy, referring to the phase diagrams of such binary alloys, it was concluded that the rate of precipitation became faster when an eutectiod temperature was getting higher or an eutectiod composition was getting lower.
Measurements of Young’s modulus and thermal expansion at −150°∼400°C and of rigidity modulus and hardness at room temperature have been carried out with Mn-Cu alloys subjected to a variety of heat treatment and cold working. It is shown that Mn-Cu alloys containing 6.00∼57.46%Cu slow-cooled after heating for 1 hr at temperatures below 80°C from the melting points have distinct antiferromagnetic Néel points in the thermal expansion and Young’s modulus temperature curves, revealing Elinvar property. The values of Young’s modulus in annealed state were higher than those in the cold-worked or the water-quenched state, the difference being remakably large in the (α+γ) phase on the Mn side. The hardness of Mn-13∼17%Cu alloys was very high regardless of the heat treatments involved. The temperature coefficient of Young’s modulus undergo a wide variation with annealing, water-quenching, cold-working, and reheating after water-quenching or cold-working, and also with alloy composition. The curves of temperature coefficient of Young’s modulus vs. composition generally have large maxima and minima in positive and negative signs, thus indicating the Elinvar property. The highest positive temperature coefficient of Young’s modulus in the annealed state was 14.7×10−5 for the composition of 56.40%Cu. Further, the changes in rigidity modulus and its temperature coefficient with heat treatment, cold working and composition bear a close resemblance to those in Young’s modulus and its temperature coefficient.
Please see pdf.
Wrong:[in Japanese], Fig. 2, [in Japanese], (12) R. S. Dean: Trans. ASM, 40 (1948), 355, 381., [in Japanese]
Right:[in Japanese], [Please see PDF], [in Japanese], (12) P. Makhurane and P. Gaunt: J. Phys. C (Solid State Phys.), 2 (1969), 959., [in Japanese]