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Metallographic structure, dendrite cell size and mechanical properties of Al-6.6 wt. pct. Si-0.6 wt. pct. Mg alloy, unidirectionally solidified under various solidification conditions, have been studied. It has been found that the transition from columnar to equiaxed structure occurs when the ratio of temperature gradient (G) to rate of solidification (R), G/R, is smaller than a constant value. Dendrite cell size has been measured to be proportional to the negative one-fourth power of the cooling rate, and has been also measured to be proportional to the 0.22 power of local solidification time. Tensile strength increases as the dendrite cell size decreases and the cooling rate increases.

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The rate of absorption of hydrogen in stagnant liquid silver-copper alloys has been measured using a steady state gas-liquid metal diffusion cell technique. The appropriate solution of Fick`s first law has been used to calculate the hydrogen permeability (R_H). The rate of hydrogen dissolution in liquid silver-copper alloys has been found to be controlled by diffusion of hydrogen in liquid metal. Permeabilities of hydrogen in liquid silver-copper alloys in the temperature range of 1000℃ to 1160℃ can be described by the following Arrhenious type equations; R_H pure Ag=5.47×10^(-4)exp{(-16872.9±700.0)/RT} wt% ㎠/sec R_H Ag-1% Cu alloy=2.27×10^(-4)exp{(-13859.6±1068.7)/RT} wt% ㎠/sec R_H Ag-3% Cu alloy=2.16×10^(-4)exp{(-13227.8±673.9)/RT} wt% ㎠/sec R_H Ag-5% Cu alloy=2.15×10^(-4)exp{(-12719.6±1351.4)/RT} wt% ㎠/sec R_H Ag-7% Cu alloy=1.79×10^(-4)exp{(-11909.7±1565.6)/RT} wt% ㎠/sec The permeability of hydrogen in liquid silver-copper alloys increased and the activation energy of permeation of hydrogen decreased with increasing copper concentration at constant temperature.

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A study has been made of the structure and properties of complex aluminum bronzes containing 8-8.5% Al and 2-6% of Ni and Fe respectively. The relation among Fe/Ni ratio, and mechanical property has been also studied. The results were as follows. 1. Mechanical properties of castings was increased as Fe/Ni ratio increases. 2. Activation energy for precipitation hardening was decreased as Ni and Fe increases. It`s range of specimen added Ni was from 26,000 to 35,000 ㎈/㏖, and by adding Fe from 24,000 to 28,000 ㎈/㏖. 3. The creep rate under the condition as T=873°K, σ=2.3 ㎏/㎟ was increased with the increasing Ni content and was decreased with the increasing Fe content. The creep rate by adding Ni was 1.0×10^(-4)∼1.20×10^(-4)/min, by adding Fe was 0.33×10^(-4)∼0.73×10^(-4)/min. Hot strength was increased by adding Fe and decreased by adding Ni

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Graphite spheroidization, matrix, fading, mass effect and acid-resistance in the range of various additional amount of Fe-Si-Mg in spheroidal graphite castiron were studied. The important results obtained are as follows. 1. When a great amount of Fe-Si-Mg was added to thec aast iron, radiated spheroidal graphite was formed, where Si and Mg in the additional alloy promoted to radiate the spheroidal graphite. 2. The more amount of Fe-Si-Mg was added to the cast iron the more ferrite was appeared in the matrix and the hardness was increased by the effect of silicon in the additional alloy. 3. When a great amount of additive was added, the more the carbon content was and the faster the cooling velocity was, the less radiated spheroidal graphite was formed. 4. Radiated spheroidal graphite which was formed by a great amount of additive became perfect spherical shape gradually as the fading time went by. 5. The more additional amount of Fe-Si-Mg was, the less the effect of inoculation became. 6. As the amount of additive increased. Corrosin-resistance in HCl solution was improved lineously by the effect of Si in the Fe-Si-Mg alloy.

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In lead and tin solder antimony is one of the adding elements. Antimony acts as a preventive of tin-pest and a hardening additive as well as an undesirable impurity (depending on the amounts). The effect of antimony on the wettability of 40-60 lead-tin solder on copper plate was studied. The required maximum content of antimony was obtained by measuring the contact angle in a sessile drop method. The effects of temperature and time on the contact angle were also studied. The contact angle increases with antimony content at a given temperature. By using the arbitrary limit of contact angle set by experience, 75°, the possible maximum contents of antimony in 40-60 lead-tin solder were found, which were about 1.9 wt. % at 350℃ and higher than 3 wt. % at 400℃. Since the contact angle even without antimony exceeded this limit at 300℃, this temperature had better be avoided.

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The effects of SiC in molten borax on the electro-boronizing have been studied quantitatively and the effects of SiC in molten borax deteriorated by Fe on the electro-boronizing also have been studied. The more the amount of SiC is in the molten borax, the more the boronized depth increases and microhardness of boronized layer increased too. However at the lower temperatures, the more the amount of SiC is in the molten borax, the less the boronized depth is. Because the fluidity of the electrolyte having more SiC content becomes worse at lower temperature. Especially, when the boronizing is carried out in the electrolyte whose composition is 40%SiC and 60%Na₂B₄O_7, Si diffuses into specimen faster than B and forms Fe-Si alloy at the region between boronized layer and matrix and Fe-C layer is also formed in the region by C diffused with B, Si. Therefore, The separation of boronized layer is apt to occur easily, because microhardess of this region is increased. The more the amount of SiC is in the molten borax, the greater the activation is. The molten borax deteriorated by Fe is recovered in ability of boronizing by addition of SiC.

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The effects of Ni addition on the precipitation of carbides and pearlitic constituents in Hadfield steel were investigated by means of microscopy and hardness measurements. From this experiment the following results were obtained. 1) By the addition of Ni, the temperature range of precipitation of carbides became narrow, but that of pearlitic constituents was nearly unchanged. 2) Carbides were precipitated preferentially in the range of 600-700℃ and pearlitic constituents at 600℃. 3) Except the lower temperature range, carbides were precipitated in the shape of film at the grain boundaries in the earlier heating stage, but with the increase in heating time and temperature, the shape of carbides was changed as follows; acicular, granular and chain-like carbides. 4) Increased hardness was mainly affected by pearlitic constituents precipitation rather than acicular carbides. 5) With the increase in carbon contents, the pearlitic constituents precipitation rate was accelerated remarkably by the addition of Ni in Hadfield steel.

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A method of case hardening treatment on the alloy tool steel (SKD-11) have been studied by using molten salt bath composed of K₄Fe(CN)_6, NaOH, Na₂SO₄ and NaCl where the weight ratio of major two compounds was fixed to 88 : 8.5 but those of Na₂SO₄ and NaCl were varied in the range of 0-3.5%. The experiments were conducted in the molten salts at 550℃ for various periods of time and different salt compositions have lead to the following: The significance in the weight ratio of Na₂SO₄ is recognized considerably and the optimum condition of treatment is obtainable when Na₂SO₄ content in the bath is as much as 2.0% and soaking for 90 minutes. In the optimum condition of treatment the effective thickness and hardness of hardened layer attainable is respectively 111μ and Hv 620.

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