Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
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Volume 75, Issue 8
Displaying 1-8 of 8 articles from this issue
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Regular Articles
  • Structural Analysis of Nano-Granular Metal-Fluoride TMR Films
    Nobukiyo Kobayashi, Takao Tsurui, Shigehiro Ohnuma, Tsuyoshi Masumoto
    Article type: Regular Article
    2011 Volume 75 Issue 8 Pages 419-423
    Published: 2011
    Released on J-STAGE: August 01, 2011
    DOIhttps://doi.org/10.2320/jinstmet.75.419
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      We have investigated the structure of (Fe, Co)-Mg-F nano-granular TMR films by HRTEM. These films have nano-granular structure which consists of Co or Fe nano-granules with diameter of 2-3 nm surrounded by thin intergranules of MgF2 with crystal structure. The structure of Co granules is crystalline, whereas the one of Fe is an amorphous state, which may be attributed to small MR ratio of 42 vol%Fe-(Mg0.32F0.68) film compared with the theoretical one calculated from spin polarization (P) of Fe crystal.
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  • Effect of Alumina Content on the Mechanical Properties of Alumina Particle Dispersion Magnesium
    Shigehiro Kawamori, Kiyoshi Kuroda, Yukio Kasuga, Masahiro Yokouchi, H ...
    Article type: Regular Article
    2011 Volume 75 Issue 8 Pages 424-431
    Published: 2011
    Released on J-STAGE: August 01, 2011
    DOIhttps://doi.org/10.2320/jinstmet.75.424
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      To enhance the mechanical properties of magnesium (Mg) alloys, powders of pure Mg (Al2O3/Mg) dispersed with over 10 vol% alumina (Al2O3) particles were made by ball milling powder mixtures of pure Mg and Al2O3 particles with particle sizes of 0.3 and 1 μm.
       The effect of the Al2O3 content of hot-pressed discs formed from the Al2O3/Mg powders on the mechanical properties of the discs was investigated. The Al2O3 particles were found to be uniformly dispersed in the Al2O3/Mg discs. The hardness of the discs increased sharply at an Al2O3 content of 20 vol%. This is considered to be because of the excellent interfacial bonding between Mg and Al2O3 when the Al2O3/Mg discs contain a sufficient amount of Al2O3 particles and have a sufficient interparticle distance. The maximum hardness of a 20 vol% Al2O3/Mg disc (with an Al2O3 particle size of 0.3 μm) was 220 HV, which is much higher than the hardness of AZ91 Mg alloys. The bending strength of the Al2O3/Mg discs increased from 0 to 10 vol% Al2O3 and then decreased from 20 vol% Al2O3. It is considered that the 0 and 10 vol% discs have similar fracture deflections and that the 10 vol% discs with Al2O3 particles can withstand higher compression and tension forces than the 0 vol% discs which do not contain any particles. The reason for the lower bending strength of the 20 vol% Al2O3 disc is thought to be because it is harder and more brittle, making it easier for voids to form in the discs, and thus making it easier for cracks to propagate on the specimen surface.
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  • Pyrometallurgical Recovery of Indium from Dental Metal Recycling Sludge by Chlorination Treatment with Ammonium Chloride
    Osamu Terakado, Takashi Saeki, Ryoji Irizato, Masahiro Hirasawa
    Article type: Regular Article
    2011 Volume 75 Issue 8 Pages 432-437
    Published: 2011
    Released on J-STAGE: August 01, 2011
    DOIhttps://doi.org/10.2320/jinstmet.75.432
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      In the present paper we address the novel chlorination process for recovery of indium selectively from dental metal recycling sludge which contains considerably high amount of indium. The process is based on the utilization of ammonium chloride, NH4Cl, as chlorination reagent. It was found that indium could be successfully recovered from the sludge in the form of volatile indium chloride by heating the mixture of sludge and NH4Cl at the temperature of 400°C under inert atmosphere. The influence of process parameters, such as composition of NH4Cl, was investigated in order to achieve high process efficiency.
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  • Microstructure of Surface Corrosion Layer of Bronze Coin Headontongbo Fabricated in the Koryo Period (11th Century)
    Jung Eun Choi, Masahiro Kitada
    Article type: Regular Article
    2011 Volume 75 Issue 8 Pages 438-444
    Published: 2011
    Released on J-STAGE: August 01, 2011
    DOIhttps://doi.org/10.2320/jinstmet.75.438
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      The microstructure of the surface corrosion layer of the bronze coin Headongtongbo fabricated in the Koryo period (11th-12th centuries) in Korea has been investigated. The coin was first produced in 1097 and had been circulated in the first Koryo dynasty. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to determine the structure of the specimen. The matrix composition of the specimen is Cu-6.1 mass%Sn-1.4 mass%Pb-0.5 mass%S. Metallic phase αCu, Pb and Cu2S are observed in the bronze matrix. The surface corrosion layer consists of brown, grayish brown and greenish corrosion matters. The closer to the surface, the Cu concentration decreases. Conversely, the closer to the surface, Pb and Sn concentrations increase. The brownish layer consists of CuO. A mixture of Cu2O, CuO and SnO2 is observed from the grayish brown layer on the αCu matrix. The greenish corrosion layer is malachite (Cu2(CO3)2(OH)2) containing Sn and Pb. Chlorine introduced from the environment is detected from a part of the corrosion layer.
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  • Mechanical Properties and Biocompatibilities of Zr-Nb System Alloys with Different Nb Contents for Biomedical Applications
    Toshikazu Akahori, Mitsuo Niinomi, Masaaki Nakai, Harumi Tsutsumi, Yus ...
    Article type: Regular Article
    2011 Volume 75 Issue 8 Pages 445-451
    Published: 2011
    Released on J-STAGE: August 01, 2011
    DOIhttps://doi.org/10.2320/jinstmet.75.445
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      The microstructures, mechanical properties, and biocompatibilities of as-solutionized Zr-Nb system alloys with different Nb contents for biomedical applications were investigated. The microstructures of Zr-5 mass%Nb, Zr-10 mass%Nb, and Zr-20 mass%Nb alloys subjected to solution treatment (ST) consist of α′, ω, and β phases while the microstructure of Zr-30 mass%Nb alloy subjected to ST consists of almost all single β phase. Young's modulus of Zr-20 mass%Nb alloy shows the lowest value of 63 GPa among the others alloys although the tensile strength and 0.2% proof stress decrease because of decrease in volume fraction of ω phase while Zr-10 mass%Nb alloy with a large amount of ω phase shows the highest values of Young's modulus, tensile strength, and 0.2% proof stress. The elongations of Zr-20 mass%Nb and Zr-30 mass%Nb alloys show relatively high values of 22% and 24%, respectively. The cell viability and bone-bonding characteristics of Zr-Nb system alloys are improved with increasing Nb content. Therefore, it is considered that Zr-Nb alloys have relatively high biocompatibility and belong to bio-inert metallic biomaterial.
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  • Mechanical Properties and Frictional Wear Characteristics of Biomedical Zr-20 mass%Nb Alloy Subjected to Surface Hardening Treatment
    Toshikazu Akahori, Mitsuo Niinomi, Masaaki Nakai, Harumi Tsutsumi, Yus ...
    Article type: Regular Article
    2011 Volume 75 Issue 8 Pages 452-459
    Published: 2011
    Released on J-STAGE: August 01, 2011
    DOIhttps://doi.org/10.2320/jinstmet.75.452
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      The frictional wear characteristics, mechanical properties, and biocompatibilities of biomedical Zr-20 mass%Nb alloy (Zr-20Nb) subjected to solution treatment (ST) and air-oxidizing process (AOP) were investigated. Vickers hardness of the specimen surface of Zr-20Nb subjected to AOP at 973 K, 1073 K, and 1123 K are approximately 4.5 times larger than that of Zr-20Nb subjected to ST. Young's modulus of Zr-20Nb subjected to AOP increases with increasing AOP temperature up to 1073 K. 0.2% proof stress, tensile strength, and elongation of Zr-20Nb subjected to each AOP decrease proportionally with increasing AOP temperature, and is inferior to those of Zr-20Nb subjected to ST because of the growth of oxide layer with a large amount of micro-cracks and the diffusion of oxygen into the subsurface. Frictional wear loss of Zr-20Nb subjected to each AOP decreases drastically as compared to that of Zr-20Nb subjected to ST. Bone-compatibility of Zr-20Nb subjected to AOP at 973 K is better than that of AOP at 1073 K because of the existence of some cracks and partial exfoliation of oxide layer.
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  • Verification of Rate Equation for Recombination between Self-Interstitial Atoms and Vacancies
    Takafumi Amino, Kazuto Arakawa, Hirotaro Mori
    Article type: Regular Article
    2011 Volume 75 Issue 8 Pages 460-464
    Published: 2011
    Released on J-STAGE: August 01, 2011
    DOIhttps://doi.org/10.2320/jinstmet.75.460
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      Rate equation (RE) and kinetic Monte Carlo (KMC) simulation are widely used to understand the accumulation process of lattice defects upon high-energy particle irradiation. RE is more suitable for the simulation of longer term processes in comparison with KMC simulation. However, the accuracy of the results obtained by RE has not yet been clearly established. In the present study, the accuracy of RE for the reaction between self-interstitial atoms and vacancies in a body-centered cubic lattice is verified using a KMC method. The results show that the accuracy of RE reduces when the spatial correlation among defects is not negligible.
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