An experimental investigation of the sintering process of nickel-bonded titanium carbides was carried out by means of dilatometric and metallographic methods. Linear shrinkage of compacts of mixed powders of nickel and titanium carbide of various compositions (0, 10, 20, 30, 40, 50 and 75% nickel in the weight ratio) was measured during sintering with a silicon carbide dilatometer. The temperature was raised at the rate of 250°C/hr up to 1500°C and kept constant for 1 hr and then lowered at the same rate. In most cases, except for 0% and 75% nickel, linear shrinkage of the compacts was very slight up to about 1200°C, but the abrupt shrinkage corresponding to the appearance of a liquid phase was observed over the temperature range of 1200∼1350°C. The total shrinkage during sintering increased, while the starting temperature of the abrupt shrinkage decreased with the increase in nickel content. The linear shrinkage at the temperature of 1500°C was proportional to logarithm of sintering time. It was shown by the metallographic examination that the shape of carbide grains changed from round to angular with the increase in nickel content. The grain size and the sphericity index of titanium carbide, however, did not change so much with the nickel content under the same sintering conditions. The change in the shape of carbide grains may be attributed to the continuity of a binder phase in compact.

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The effects of sintering atmosphere, temperature and the amount of metal binder on the shape and the size of carbide grains in nickel-bonded titanium carbides were studied by a metallogrsphic method.
Five different mixtures of powders of titanium carbide and nickel, containing 10, 20, 30, 40 and 50 wt% Ni, were prepared by ball milling for 25 hr with methyl alcohol. Besides, the mixtures to which 5% TiO₂ was added were also prepared. Compacts of 12 mmφ×10 mm were pressed at 1 t/cm², which were sintered at 1500°C in a graphite boat in either dry hydrogen or argon and then quenched in water. The specimens were cut into two and polished with diamond paste. The grain size and grain shape were determined statistically from the micrographs.
It was found that the size and shape of carbide grains varied with the amount of metal binder, i.e., the amount of liquid phase existing during the sintering process. The specimens containing more than 30% Ni showed that the grain size was the function of the sintering temperature, being independent of the composition. Those of less than 20% Ni, however, proved that the grain size decreased with the decrease in the amount of metal binder. In the absence of oxysen the fraction of angular carbide grains increased with the amount of metal binder, while in the presence of oxygen the increase of spherical grains was observed. In thecase of the sintering at a temperature as low as 1400°C, the grain growth and the effects of the atmosphere and the amount of metal binder on the grain shape were greatly reduced.

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In order to determine the characteristics and controlling mechanisms of the nonbasal slip which is the secondary slip system of several hcp metals such as magnesium, tensile tests were performed on single crystals of high purity magnesium having a special orientation whose tensile axis is parallel to the (0001) basal plane, and thereby the temperature and strain rate dependence of flow stress of the nonbasal slip was investigated.
Following are remarkable characteristics of the nonbasal slip in magnesium: (1) The basal slip has a wide easy glide region more than 100% in shear strain, while the nonbasal slip has no plastic region corresponding to this easy glide and rapid work hardening occurs at the early stage of deformation. Below 100°C, this rapid hardening continues up to fracture and the elongation to fracture is limited to only several per cent. At above 200°C, however, the work hardening rate becomes practically zero during further deformation beyond a certain strain. With rising temperature, this critical strain decreases and the ductility is markedly developed. (2) The strain rate dependence of flow stress is very remarkable and is about 10² times as large as that of the basal slip observed at low temperatures. (3) The temperature dependence of the flow stress is also very remarkable. Below about 350°C, the flow stress increases rapidly with lowering temperature, while above this temperature the flow stress does not so much depend on the test temperature. (4) The slip bands observed are short in length and occurs in association with frequent cross slips. These results, indicate that the superjogs formed by easy cross gliding of the screw dislocations from the nonbasal plane to the primary slip (0001) plane, would play an important role in the nonbasal slip. It is further considered that the thermally activated process which controls the nonbasal slip is varied with temperature as follows; when the strain rate is 2.3×10⁻³ sec⁻¹, the interaction of glide dislocations with trail dislocation loops left behind moving screw dislocations from room temperature to about 250°C, the climbing motion of the superjogs on screw dislocations from about 250°C to 350°C, and the process of bowing out on the nonbasal plane of the constricted and recombined screw dislocations initially extending on the basal plane about 350°C.

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The Corrosion of AISI Type 304 (or 304 L) stainless steel in high temperature water (300°C, 87 kg/cm², 1000 hr) was investigated in connection with the carbon content, surface preparation, heat treatment, cold working, etc. An X-ray diffractometer was used to investigate the ferrite formation caused by cold working. The corrosion results were compared with those in boiling 40% and 65% nitric acid, 5% sulfuric acid and copper sulfate-sulfuric acid solutions. These results are summarized as follows; (1) The carbon contents and heat treatments do not affect appreciably the corrosion resistance of Type 304 (or 304 L) stainless steel in high temperature water. However, the corrosion is affected significantly by the surface finish. (2) The degree of cold working does not have a direct relation to the corrosion resistance in high temperature water. However, the ferrite caused by cold working accelerates the corrosion significantly. (3) A consistent relation is found between the corrosion in boiling 5% sulfuric acid and in high temperature water. However, the corrosion in boiling nitric acid has a poor consistent relation with the corrosion in high temperature water.

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The thermodynamic properties of the Zn-In, Zn-Sn binary and the Zn-In-Sn ternary systems have been determined from the electromotive force measurements over the temperature range of 420 to 550°. The experimental results are discussed in terms of solution theories.

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The behaviors of the impurities, Sn, Ti and Fe in the liquid-liquid solvent extraction of Ta and Nb with organic solvents are very important in the production of high purity Nb and Ta. The authors investigated the behaviors of impurities mentioned above in four solvent extraction systems of Ta and Nb, namely HF-hexone, HF-HCl-hexone and HF-H₂SO₄-hexone and HF-HNO₃-hexone systems: The results obtained can be summarized as follows: (1) By measuring the distribution ratios of Sn, Ti, Fe, Ta and Nb in each extractive system, it was found that Sn, Ti and Fe can be separated sufficiently from Nb and Ta. (2) The extractabilities of Sn, Ti and Fe increase with the mineral acid concentration at a constant HF acidity. (3) At a constant high HF acidity, 12.75 N, they decrease in the following order: HF-HCl system > HF-H₂SO₄ system > HF-HNO₃ system. (4) Sn % and Ti % of the total organic extract augment with the frequency of extraction in the HF-H₂SO₄, HF-HCl and HF-HNO₃ systems. (5) The separation ef each of Sn, Ti and Fe from Ta is easier than those from Nb. (6) In the HF-mineral acid-hexone system one can obtain an extract of higher purity than that in the HF-hexone system by selecting some suitable mineral acid concentrations and moreover by utilizing an advantage of larger coextractability of Nb and Ta.

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The method for extracting and separating Ta and Na by using the solvent extraction system, hydrofluoric acid-sulfuric acid-tributyl phoshate (TBP), was investigated. The extractability of fluotantalates and fluoniobiates from HF-H₂SO₄ solution into TBP was found to be functions of HF acidity, H₂SO₄ acidity, TBP concentration, oxide concentration, organic solvent ratio, and extraction frequency. The results obtained can be summarized as follows: (1) The Ta percentage extraction and the Ta distribution ratio increased with the increase of H₂SO₄ acidity at a const HF acidity, but decreased with the increasing HF acidity at a constant H₂SO₄ acidity. They diminished with the decrease of TBP concentration. The Nb percentage extraction and the Nb distribution ratio augmented with increasing HF acidity, H₂SO₄ acidity, and TBP concentration. (2) In general, the separation coefficient was superior in low HF acidity-low H₂SO₄ acidity, being inferior at high HF acidity-high H₂SO₄ acidity. It was little varied by TBP concentrations. (3) The percentage extractions of Ta and Nb fell with the increase of oxide concentration of aqueous solution. (4) The augmenting volume ratio of solvents and the frequency of extraction caused increases of the percentage extractions of Ta and Nb. (5) The extract made with TBP contained little impurities. (6) The HF-H₂SO₄-TBP system has larger extractability of Ta and Nb, particulary Nb, and is higher in purity the organic extract than the HF-H₂SO₄-hexone system which is being used as the industrial extraction system for liquid-liquid extraction of Ta and Nb.

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Cold rolling behaviours of a commercial pure titanium have been studied by means of transmission electron microscopy. The results indicates: (1) In cold rolled titanium, there are a number of tangled dislocations which have often been observed in cold worked face centered cubic metals. (2) In 16.7% cold rolled Ti, imperfect structures with a high concentration of tangled dislocations were observed and a great number of uniformly distributing dislocation loops were observed. They were also observed in 50.0% rolled Ti.

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The effects of ausforming on the hardness and structure of Fe-Ni and Fe-Ni-C alloys were examined. The results of microhardness tests showed that some amount of the carbon content might be essential for the strengthening of steel by ausforming. Optical micrographs showed that a martensite plate in the ausformed specimen was finer than that in the unausformed, and was bent and kinked. Transmission electron micrographs and electron diffraction patterns of ausformed Fe-Ni-C alloy showed that: (1) There were strong stresses within and around the martensite plate. (2) The twin faults in the martensite crystal were also recognized. (3) A cloudy distribution of dislocations was observed in the martensite plate, and the carbon atoms might migrate on these dislocations. The ausformed specimen was hardened mainly by precipitation and/or dispersion of carbides. (4) Severely kinked martensite plates were frequently observed. (5) The lattice orientation relationship between austenite and martensite in the ausformed Fe-Ni-C alloy approximately obeyed the usual law in the same way as in the unausformed.

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Creep-rupture tests have been performed on the austenitic heat-resisting steel LCN 155. The rupture elongation of the solution-treated or insufficiently aged specimens of this kind of steel considerably decreased under a certain range of stress (or over a certain range of creep-rupture time). The rupture took place along the grain-boundaries and marked intergranular corrosion occurred by etching in such a specimen ruptured with small elongation. These features are common to many other austenitic steels or super alloys. Therefore, the present paper is intended to throw light on the mechanism which induced a marked decrease in rupture elongation and on the reason why this decrease was inevitably attended with marked intergranular corrosion. The investigations were performed in details on LCN 155 steel and the electro-chemical examination of intergranular corrosion was also made on chromium steels, from which the following points have been made clear.
(1) In the rupture test chromium atoms, which are usually added in rather great quantities to austenitic heat-resisting steels to give them oxidation resistance, diffuse to grain-boundaries and precipitateas carbides. Therefore, the chromium is depleted in the matrix near grain boundaries and thereby marked intergranular corrosion by etching takes place.
(2) The chromium distribution in the depleted zone was determined from the distribution of anodic equilibrium potential in the microscopic region of matrix in the vicinity of grain-boundary carbides. It was made clear that the concentration in the matrix at the interface with the carbide precipitate growing in a boundary was less than 1 wt% approximately.
(3) According to the calculation based on the measured chromium concentration gradient, the Kirkendall effect was supposed to occur with the diffusion of atoms during the precipitation of carbides. The relative excess vacancy concentration due to the Kirkendall effect was calculated and the excess ratio of more than 10² was obtained for LCN 155 at the aging period of 5 hr at 700°C. The value of about 10 was found to continue for a fairly long period of time.
(4) The above excess vacancies may promote the formation and growth of voids in the vicinity of grain boundaries in the rupture test under a stress which exceeds a eartain value. The voids develop to cracks and eventhally result in rupture. Therefore, one may expect that the reduction in the creep-rupture elongation of solution-treated or insufficiently aged austenitic steels is due to this mechanism.

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The cooling curves at the center and surface of silver and steel specimens with various diameters, quenched into various quenchants, were measured and examined. The effects of size, shape, thermal properties and measuring position were discussed. A curve showing only the cooling characteristics of quenchants independent of size, shape or material of specimen was introduced, which will hereafter be referred to as the “master cooling curve”. The curve was valid regardless of whether the specimens obeyed Newton’s law of cooling. The concept of the master cooling curve is widely applicable to the quantative determination of steel hardening.

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