著者

服部 伴之 山口 哲央 間嶋 俊雄 寺嶋 和夫 吉田 豊信

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.63, no.1, pp.68-73, 1999

被引用文献数

3

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Hot cluster epitaxy (HCE) is a novel high-rate epitaxial growth mechanism discovered in the study of the plasma flash evaporation method. In HCE, the main deposition species are thermally activated, nanometer-scale clusters (hot clusters), which have unique characteristics such as high internal energy and high sticking probability even at high substrate temperature. Actually, with HCE, deposition of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7&minus;<I>x</I></SUB> epitaxial films at a growth rate of 16 nm/s on the SrTiO<SUB>3</SUB> substrate has been achieved. However, films thicker than 2 &mu;m could not be obtained so far. In this paper, we discuss the &ldquo;charge-up&rdquo; effect of clusters and insulating substrates in a plasma environment as a retarding factor for film growth. Probe measurements and the biasing deposition clarified the charge-up of clusters were charged up during deposition. It was found that more than 60% of the clusters were negatively charged. By using conductive substrates of Nb doped SrTiO<SUB>3</SUB>, or changing Ar composition in Ar-O<SUB>2</SUB> plasma, we could deposit monolayer-smooth epitaxial YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7&minus;<I>x</I></SUB> films thicker than 3 &mu;m, with excellent properties; the full width less than 0.14&deg; at half maximum of the X-ray rocking curve of the (005) peak, and the superconducting transition temperature of 92 K. These results suggest the future role of HCE in epitaxial thick film deposition.

著者

渋谷 陽二 鳥生 純一 冨田 佳宏

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.61, no.8, pp.696-701, 1997 (Released:2008-04-04)

参考文献数

23

被引用文献数

1 1

---

A stress-induced phase transformation phenomenon is one of the hierarchical mechanical behaviors in which atomistic rearrangements are simultaneously and dually reflected to macroscopic strength of material. It has so far been recognized as one of the bifurcation problems in the fields of thermodynamics and continuum mechanics. Softening of phonon dispersion curves has also been acknowledged as precedence of transformation as well. Movements of atoms in an α-iron under uniaxial tension are first traced by the molecular dynamics (MD) simulations on the assumption of a constant applied stress ensemble proposed by Parrinello & Rahman. Stress dependency of phonon dispresion curves obtained from the deformed lattice structures are then examined. Bifurcation conditions derived from positive definiteness of strain energy in the whole deformed matters are, at the same time, investigated using analytical elastic constants defined from only an atomic configuration and the force constants which are the second derivative of an employed interatomic potential. It is found that softening of phonon dispersion curves, especially the long-wavelength acoustic branch, could correspond to the macroscopic bifurcation conditions over the scale.

著者

正藤 和男 仁木 栄次

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.37, no.5, pp.493-495, 1973 (Released:2008-04-04)

参考文献数

9

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The mass absorption coefficients for X-ray of 13.3 Å (=CuLα) have been determined by the use of EPMA and a special composite target.The composite target was prepared by means of the evaporation of Al, Cr, Ni, Zn, Se, Zr, Sn, Sb, Gd, Au, Pb or Bi on Cu base in vacuum (∼10−5 mmHg).The mass absorption coefficients of these metals for the CuLα line were determined from the experimental results by the following equation:(This article is not displayable. Please see full text pdf.) \ oindentHere, I1 and I2 are relative intensities of CuLα line measured from the composite target with Al surface film of t1 g/cm2 and another surface film of t2 g/cm2, respectively, where t1 and t2 are the “equivalent thickness” to each other, and θ is a take-off angle of X-ray.

著者

吉武 道子

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.78, no.11, pp.408-414, 2014 (Released:2014-11-01)

参考文献数

18

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At metal oxide (AO)-metal (M) interfaces, metal (M) atoms can make bonds with metal oxide through either oxygen (O) atoms or metal (A) atoms that composed of the oxide. Examples of the identification of an element at the interface in atomic level using photoelectron spectroscopy have been demonstrated for alumina, zinc oxide and cerium oxide. Software, which predicts interface bonding according to a method developed by the author, and which is open to public, is presented. It is demonstrated that the difference in the interface bonding species has great influence on the band offset, the energy difference between the Fermi level and the valence band in the band energy diagram. The observations of such difference in band offset using photoelectron spectroscopy are also provided.

著者

野田 哲二 工藤 清勝 佐藤 教男

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.37, no.9, pp.951-957, 1973

被引用文献数

11

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The anodic passivation film formed on iron in neutral borate-buffer solution has been studied by using ellipsometric, electrochemical, and gravimetrical techniques. The film can be dissolved from its outer surface by applying a cathodic current in borate-buffer solution at pH 6.35 in which the reductive dissolution,<BR>(This article is not displayable. Please see full text pdf.) <BR>\oindentproceeds at 100 per cent current efficiency. Ellipsometric measurements carried out during the galvanostatic-cathodic reduction of the film in this solution reveals that the film consists of two layers, an inner layer with the optical constant 3.0&minus;0.5<I>i</I> and an outer layer with the constant 1.8&minus;0.1<I>i</I>. It is also shown that the density of the inner layer is in agreement with that of &gamma;-Fe<SUB>2</SUB>O<SUB>3</SUB>.<BR>The inner layer thickness increases linearly with the passivating potential, and the potential extrapolated at zero thickness of the inner layer corresponds to the equilibrium potential of the anodic formation of &gamma;-Fe<SUB>2</SUB>O<SUB>3</SUB>,<BR>(This article is not displayable. Please see full text pdf.) <BR>\oindentThe outer layer, however, is not directly related to the anode potential. <BR>Thermo-gravimetrical measurements indicate that the film contains some amount of water which is concentrated in the outer layer. The average composition of the outer layer is estimated as Fe(OH)<SUB>3</SUB>.<BR>A film model is proposed in which the inner layer of anhydrous &gamma;-Fe<SUB>2</SUB>O<SUB>3</SUB> is the cause of the potential drop in the film producing a field intensity of 5.6&times;10<SUP>6</SUP> V/cm and the outer layer of hydrous ferric oxide depends on the solution environment and passivation process.

著者

中島 篤之助 高橋 正雄 河口 広司

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.22, no.11, pp.564-568, 1958

被引用文献数

1

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A method has been developed for the determination of rare earth elements including yttrium in uranium and its compounds. The greater portion of the uranium is separated from the rare earths by ether extraction. The rare earths are then precipitated as fluorides and subsequently purified as hydroxides. Lanthanum was used as the carrier. The efficiency of the above separation procedures was studied by means of the radioactive tracer Eu<SUP>152+154</SUP>. The final determination was carried out spectrographically by the copper-spark method. Five rare earth elements which showed extremely high neutron absorption were investigated, and their limits of detection (sensitivity) and recoveries from U<SUB>3</SUB>O<SUB>8</SUB> are reported.

著者

諸石 大司 志田 善明

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.42, no.3, pp.316-323, 1978 (Released:2008-04-04)

参考文献数

21

被引用文献数

1 1

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The oxidation of pure titanium was studied in superheated steam at 400∼550°C. The effects of prior cold working and several heat treatment conditions on the oxidation were examined and also the effects of the addition of small amounts of iron and oxygen were investigated. The oxidation mechanism of pure titanium is discussed in relation to the scale structure and the oxidation kinetics. Hydrogen absorption rate was also measured. As a result, the following conclusions were drawn:(1) The oxidation of pure titanium in steam was faster than in air and breakaway oxidation was observed above 500°C after the specimen had gained a certain weight. Prior cold working and heat treatment conditions scarcely affected the oxidation rate, whereas the specimen containing small amounts of iron and oxygen showed a little more rapid oxidation.(2) At 500 and 550°C a dark grey inner scale and a yellow-brown outer scale were formed. The outer scae was apt to exfoliate after the occurrence of breakaway oxidation. At 400 and 450°C only a dark grey scale was observed. All of these oxides were identified as the rutile type, TiO2. Furthermore, the presence of a thin and uniform oxygen rich layer beneath the external scale was confirmed at all test temperatures.(3) The measured weight gain approximately followed the cubic rate law; this would be expected for the following reason; one component of the weight gain is due to the dissolved oxygen, the amount of which remains constant after the early stages of oxidation. The second component is due to the parabolic growth of the external TiO2 scale. When these contributions are added a pseudo-cubic weight gain curve results.(4) It was shown that 50 percent of the hydrogen generated during the oxidation was absorbed into the metal.

著者

松井 光彦

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.64, no.5, pp.403-406, 2000

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Recently sodium ionic conductors such as NASICON (Na<SUB>3</SUB>Zr<SUB>2</SUB>Si<SUB>2</SUB>PO<SUB>12</SUB>) have been used as the solid electrolyte for EMF(electromotive force) type CO<SUB>2</SUB> sensors. However, it has been hard to obtain a sufficiently high quality in this type of sensor, partly due to the low humidity-resistance of NASICON and partly because of its poor initial response of EMF to CO<SUB>2</SUB> pressure.<BR>For the purpose of improving the humidity-resistance and the initial response of EMF of the solid electrolyte CO<SUB>2</SUB> sensors, Li<SUB>2</SUB>TiSiO<SUB>5</SUB> is employed as the sensing material instead of NASICON. It is composed of the following electrochemical cell:<BR>(This article is not displayable. Please see full text pdf.) <BR>The electrochemical reaction is in good agreement with the Nernst equation, and reacted electron is calculated as 2.04. The sensor fabricated with Li<SUB>2</SUB>TiSiO<SUB>5</SUB> shows good linearity when it is exposed to an atmosphere of 90% relative humidity at 60&deg;C. The initial 90% response of EMF is steadied within 4 min. These experimental results make it possible to use the sensor in the environments.

著者

山田 昭弥 白田 光利 Rizal C. L. S. 宝賀 剛 上田 勇治

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.66, no.9, pp.869-872, 2002 (Released:2008-04-24)

参考文献数

13

被引用文献数

4 5

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Pulse electrodepositon is a useful technique with which it is possible to achieve atomic-scale control of the layer composition, thickness of the multilayer and the grain size in ferromagnetic films by regulating the pulse amplitude and width. It is possible to fabricate ferromagnetic films with various magnetic properties from a single electrolytic solution containing more than two kinds of metallic ions, by changing the step pulse wave. Multilayer films composed of a Ni-rich layer with high coercive force, an Fe-Ni layer with low coercive force, and a nonmagnetic Cu layer were produced by controlling the step pulse potential from a single electrolytic solution containing Fe, Ni and Cu ions. Moreover, we are able to produce thinner ferromagnetic films consisting of multiple layers with magnetic characteristics such as a wide variation in coercive force, high susceptibility, and large magnetoresistance effect by controlling the time interval of the step pulse.In this study, we investigated the relationships between the magnetic field dependence of the magnetoresistance effect and the film preparation conditions for composition-modulated Fe-Cu-Ni alloy films produced by the pulse electrodeposition method. The MR ratio observed in the film has maximum values of 3.4% and 9% at 300 K and 5 K, respectively. A highly sensitive change of the electric resistance was obtained at a low magnetic field.

著者

吉原 一紘 新居 和嘉

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.47, no.11, pp.941-949, 1983 (Released:2008-04-04)

参考文献数

12

被引用文献数

4 2

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The surface composition of 18-8 stainless steel doped with boron and nitrogen at high temperatures was observed in vacuum with AES and XPS.The precipitation of boron nitride was found on the surface of the stainless steel. At the first stage of heating, a thin layer of boron nitride flowed out from grain boundaries and spread on the surface, replacing phosphorus and sulfur which segregated all over the surface. As the heating time was prolonged, parts of the thin layer of boron nitride increased in thickness. The thickness increased in proportion to the square root of heating time and became about 0.06 μm after heated at 1100 K for 432 ks. The precipitated boron nitride was not replaced by the most surface active element, sulfur, and remained stable on the surface. On the surface of the stainless steel, however, there existed areas not covered with boron nitride after prolonged heating. On these uncovered areas, sulfur segregated.The precipitated boron nitride layer was inert to the adsorption of gases. Therefore, this stainless steel is a superior candidate material for vacuum vessels.

著者

田中 眞奈子 北田 正弘

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.73, no.10, pp.778-785, 2009 (Released:2009-10-01)

参考文献数

10

被引用文献数

5 6

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The metallurgical microstructure and mechanical properties of the steel barrel of a Japanese matchlock gun fabricated in the Edo period have been investigated. The purpose of this work is to obtain modern materials-science data of the Japanese matchlock gun and to study the manufacturing technique of the steel barrel. Test pieces are cut from the center, the muzzle and the screw of the barrel. The carbon concentration is determined by chemical analysis. The metallurgical microstructure and nonmetallic inclusions of the barrel are observed using an optical microscope and a scanning electron microscope (SEM). Test pieces for measuring the mechanical properties are cut from the gun. To evaluate the hardness, Vickers hardness (Hv) is used. The stress-strain curve, tensile strength and elongation of the gun are obtained.    The carbon concentration is 0.01∼0.1mass% for the center of the barrel, 0.04∼0.1 mass% for the muzzle of the barrel, 0.05∼0.5 mass% for the front sight (Saki-meate in Japanese) and 0.13∼0.3 mass% for the male screw. The distribution of nonmetallic inclusions in the center and in the muzzle of the barrel suggest that the barrel was fabricated by a manufacturing technique called Udonbari (in Japanese). The metallurgical microstructure of the specimen taken from the muzzle of the barrel in the vertical direction suggests that the barrel and a front sight were joined mechanically. Both male and female screws were made by a cutting technique. The tensile strength and elongation are 316∼366 MPa and 25.0∼31.4%, respectively.

著者

淡路 英夫 加藤 稔也

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.62, no.8, pp.735-741, 1998 (Released:2008-04-24)

参考文献数

21

被引用文献数

4 5

---

The Griffith energy criterion for brittle fracture is extended to mode II and combined mode I-II fracture by postulating that crack extension occurs when the maximum energy release rate in non-coplanar crack extension is equal to the fracture energy rate required for the mode II or the combined mode crack extension. The fracture energy rate is considered to be proportional to the critical magnitude of the area of a frontal process zone at a crack tip for brittle materials. The area of the frontal process zone is simply assessed here from the area enclosed in the iso-stress contours of both the maximum principal stress and the maximum shear stress around a crack tip. The anticipated ratio of mode II and mode I fracture toughness, KIIC⁄KIC, is 1.20. The value of the ratio, KIIC⁄KIC, is also estimated experimentally for float glass using a disk test. The result shows that the value of KIIC⁄KIC is 1.28 which agrees quite well with the anticipated one.

著者

梅原 佳那 松野 泰也

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.80, no.4, pp.247-252, 2016 (Released:2016-03-25)

参考文献数

16

被引用文献数

1

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Previously we studied a novel process for recycling gold from secondary sources: the leaching of gold using dimethyl sulfoxide solutions containing copper bromide and precipitation with water, which could offer a number of advantages, including eco-friendliness, ease of operation and low cost. In this study, we have further investigated a more environmentally benign solvent, Propylene Carbonate (PC), with CuBr2 and KBr for the leaching and recovery of precious and rare metals. The mechanism of dissolution was investigated using electrochemical measurements. Metal wires were dissolved in a PC solution with 0.2 M of CuBr2 and 0.2 M of KBr at 343 K. Next, 10 ml of dilute sulfuric acid aqueous solution at pH 1 was added to the solution at ambient temperature and shaken to biphasically separate the dissolved metals. The contents of each element in the sulfuric acid and PC phases were measured by ICP-OES. The results of the electrochemical measurements indicated that the anodic dissolution of sample metals in the PC containing CuBr2 occurred at relatively negative potentials and was paired with the cathodic reduction of Cu2+ to Cu+. It was found that Au, Pd, Cu, Sn, Co, Ni and Zn could be dissolved at relatively fast rate, while Ag, Ta, Ti and W could not be dissolved. In addition, 98% of Au and 94% of Pd remained in the PC phase, while most other dissolved metals migrated to the sulfuric acid phase. This indicated that the dissolved Au and Pd could be effectively separated from other metals via biphasic separation with sulfuric acid. Next, the gold in the PC phase was recovered by the reduction of ascorbic acid or calcination. The cost analysis for recovering gold by this system resulted in 0.34 USD/g-Au.

著者

市川 裕士 所 竜太郎 亀山 雄高

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

pp.J2019033, (Released:2019-11-15)

参考文献数

17

被引用文献数

1

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Fine particle peening (FPP) is a surface modification process in which fine hard metallic particles project onto the substrate. During this process, shot particles that remain transfer to the substrate and form a complex and multi-layered lamellar structure in which transferred fragments are distributed in the depth direction and several tens of micrometers from the surface. Because the bond strength at each interface of this structure and its generation mechanism are unclear, the local bond strength of the laminated interface was evaluated in this study by a microscale tensile test conducted by focus ion beam facilities. In the transferred lamellar modified region, the hardness was considerably higher than that of as-received materials, and the microscopic bonding strength between the transferred copper or iron and the aluminum matrix was 300 MPa or greater. When steel particles were used with FPP, iron oxide was mainly transferred to the aluminum matrix. However, copper plating on the particles suppressed the oxidation of the steel composing the particles and, as a result, the metallic steel was transferred. The bonding strength was improved by oxidation-controlled steel particles.

著者

吾郷 真司 田中 照剛 横手 達夫 東田 賢二 小野寺 龍太

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.67, no.1, pp.34-39, 2003 (Released:2008-04-24)

参考文献数

1

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This study aims to give a mechanical explanation to manufacturing of metal (silver) foil in a traditional Japanese way in which the foils are put between Japanese papers and forged. It was clarified by forging tests carried out at various forging pressures that the forging pressure necessary for manufacturing silver foil is about 30 MPa, which is equal to one-tenth of the yield stress in a 90% rolled specimen. The test also showed that the plastic elongation of foil is of the order of 0.1% per forging (pressure is 30 MPa). This result suggests that the foil is not stretched by forging pressure, but by frictional tensile stress applied to the foil by the Japanese paper. Another test to measure the elastic property of paper showed that the Japanese paper was elongated by 0.5∼0.6% in the paper plane when it was compressed in the vertical direction at the pressure of 30 MPa. Considering the elastic strain of foil, the value of 0.5∼0.6% agreed well with the plastic elongation of foil of 0.1%. The forging tests also showed that the lower limit of foil thickness is dominated by the ability of paper not to adhere to the silver foil (removability); for example, it was 1 μm for some papers, but 0.4 μm for others.

著者

山末 英嗣 村橋 勲 奥村 英之 石原 慶一

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.71, no.9, pp.763-771, 2007 (Released:2007-09-01)

参考文献数

12

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An abandoned traditional steelmaking in Southwest Ethiopia (Dime) has been restored, and the technology and knowledge used for the operation have been metallurgically analyzed. The restoration was carried out with local blacksmiths from September to October in 2004, and the steelmaking operation including mining, construction of a furnace and charcoal production, etc was successfully performed. Produced sponge iron contains 0.31∼0.48 mass% carbon without any impurities. The yield ratio of the iron was about 40%. The collected slag contains the elements of Fe, Si, Al, K, P, Ti and Mn, which are typical components of slag. The blacksmiths used three kinds of iron ore, named “Balt”, “Bullo” and “Gachi”. The former two ores mainly consist of goethite (α-FeO(OH)) and kaolinite (Al2O3•2SiO2•2H2O). The latter includes calcium phosphate hydrate (Ca3(PO4)2•xH2O) in its white part, as well as the goethite and kaolinite. The reason why the local blacksmiths specifically selected “Gachi” as the best ore for their steelmaking was discussed from the viewpoint of slag forming ability.

著者

榊 孝 清水 要樹 崎山 和孝

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.49, no.3, pp.202-209, 1985 (Released:2008-04-04)

参考文献数

7

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The corrosion behaviour of various commercial alloys was studied by measurements of potentio-dynamic polarization curves, the change in corrosion potential with time and the average corrosion rate. The corrodent used was 48%NaOH solution at temperatures between 373 and 473 K, and the following results were obtained. The corrosion resistance of stainless steels was improved by adding nickel and chromium. Especially, immersion tests showed that ferritic stainless steels containing 27-30% chromium and austenitic stainless steels containing nickel more than 20% possessed excellent corrosion resistance. On the other hand, addition of molybdenum and copper to the stainless steels gave no protective effects as to the alkaline corrosion. When the corrodent was a 48%NaOH solution obtained by the diaphragm process, NaClO3 contained in the solution acted as an oxidizer. Its oxidation powder increased somewhat the tendency of the high chromium steels to become passive, but promoted dissolution of nickel.

著者

德永 透子 外本 和嗣 大野 宗一 松浦 清隆

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.81, no.8, pp.389-393, 2017-08-01 (Released:2017-07-25)

参考文献数

8

被引用文献数

1

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The poor corrosion resistance of Mg alloys, which is well known as one of the lightest structural metal materials, limits a wide use of these alloys. In order to dramatically increase not only the corrosion resistance but also the surface hardness of Mg alloys (AZ80), coating with A2024 Al alloy by hot extrusion has been attempted in this study. The coating was successfully realized by hot extrusion of a Mg alloy (AZ80) billet together with an Al alloy plate placed between the billet and the extrusion die. The A2024 Al alloy-coated Mg alloy exhibited an excellent corrosion resistance and no weight loss was observed after immersion in a 5 mass% HCl aqueous solution for 10 min while a weight loss of about 1500 g・m-2 was observed in case of AZ80 Mg alloy without coating under the same condition. The surface hardness of the coated alloy was increased to about 85 HV by aging for 144 h at room temperature after solution treatment for 3 h at 673 K.

著者

鄭 巍巍 庄子 哲雄 糸藤 春喜 張 建華

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.80, no.3, pp.176-185, 2016 (Released:2016-02-25)

参考文献数

18

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The purpose of this study is to analyze the microstructure and chemical composition of the oldest heavy section cast iron cannon in China, which was manufactured at the early Ming dynasty in the year of 1377 with the inscription of Hongwu. It is worthwhile to study any characteristic casting processes and advancement of the heavy section casting technology during the Ming dynasty because the cannon technology could be developed based upon the leading technology of that age. This cannon has been preserved and displayed at Shanxi Province Art Museum. Some microstructural analysis was performed on site by use of portable grinding and polishing tools for the metallurgical examination. In addition, more detailed metallurgical examination by EDX, XPS, high temperature optical microscope (OM) and DSC analysis was performed on a small sample taken from the cannon. Chemical analysis was also performed on the grinding chips and powder collected during the metallurgical surface preparation. A thermodynamic phase diagram was calculated by CALPHAD method for the material with the same chemical composition as measured. After the detailed metallurgical examination and chemical composition analysis, it turned out that the cannon has a chemical composition range of minor elements as: C: 1.36-1.8 mass%, S: 0.58-0.78 mass%, P: 0.61-0.81 mass%, Si: 0.45-0.61 mass%, and shows a uniform hypereutectoid microstructure. Taking into account the evidence of no microstructural gradient from a surface to inside which is not common in ancient decarburized cast iron, the cannon is highly likely to be made by a cast steel rather than by a cast iron.    Non-metallic inclusions are observed both by OM and by a scanning electron microscope (SEM) on the sample. A high temperature optical microscope with an in-situ heating capability was used to directly observe any phases with a lower melting temperature. Also DSC analysis was performed on the sample to examine any phase change at some specific temperature. Based upon these observations and analysis, it was concluded that the Hongwu cannon was made by cast steel with a hypereutectoid microstructure. This microstructure contained a eutectic phase in pro-eutectoid cementite, which suggests a formation of steadite Fe-Fe3C-Fe3P with a low melting temperature of 1227 K. This finding strongly suggests that, instead of cast iron technology, cast steel technology had already existed and was put in use for heavy-section cannon production during early Ming Dynasty in China.

著者

桐野 文良 大野 直志 田口 智子

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.83, no.3, pp.87-96, 2019-03-01 (Released:2019-02-25)

参考文献数

16

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The metal craft production techniques for an ancient Chinese coin named Ittou in the Shin period of ancient China were studied from material science viewpoints. This cultural artefact was manufactured in the Shin period of ancient China. An infrared image shows the surface state and the materials absorbed on the surface. According to infrared images of the cultural artefact, roughness on the surface of this coin was created on cooling during mintage. UV-fluorescence images show luminescence at corrosion products and yellow soil. In X-ray transmission images, some voids in this coin were observed, indicating the metal craft production technique used during this period. The main element of this cultural artefact is Cu and other elements are Sn and Pb. X-ray diffraction patterns indicate the presence of Cu-Sn base intermetallic compounds. Ittou coins are made from bronze. The characters on the coins were formed using an inlay technique called zougan. Yellow soil adhered to the surface of the examined coin from where it was excavated. The material used to form the characters on the coin is 10 mass% Cu-Au alloy, and flaws were observed on the surface of the characters. The compositions of ancient Kan coins produced between the east Kan and west Kan periods were also analyzed. The composition of these ancient coins was the same as that of the coin from the Shin period of old China, indicating that the same metal craft production technique was used in both periods. These techniques were improved in this period, enabling many coins to be manufactured.