Diamond-particle-dispersed-silver (Ag) matrix composites were fabricated in solid-liquid co-existent state by Spark Plasma Sintering (SPS) process from the mixture of diamond powders, Ag powders and Si powders. As the diamond powders, two kind of powders, monomodal diamond powders of 310 µm in diameter and a bimodal diamond powder mixture of 310 µm and 34.8 µm in diameter, were used. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated by heating at a temperature range between 1113 K and 1188 K for 0.45 ks during SPS process. No reaction at the interface between the diamond particle and the Ag matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. Although the relative packing density of the monomodal composite decreased from 97.4 % to 93.4 % with increasing diamond volume fraction between 50 % and 60 %, that of the bimodal composite was higher than 97 % in a diamond volume fraction range up to 65 %. The thermal conductivity of the bimodal composite was higher than that of the monomodal composite in a diamond volume fraction range between 55 % and 65 %. The coefficient of thermal expansion of the composites falls in the upper line of Kerner's model, indicating strong bonding between the diamond particle and the Al matrix in the composite.

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Silicon carbide (SiC)-particle-dispersed-aluminum (Al) matrix composites were fabricated in continuous solid-liquid co-existent state by Spark Plasma Sintering (SPS) process from the mixture of SiC powders, Al powders and Al - 5 mass% Si alloy powders. As the SiC powders, two kind of powders, monomodal SiC powders of 109.8 µm in diameter and a bimodal SiC powder mixture of 109.8 µm and 14.3 µm in diameter, were used. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated by heating at a temperature range between 798 K and 876 K for 1.56 ks during SPS process. No reaction at the interface between the SiC particle and the Al matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. Although the relative packing density of the monomodal composite decreased from 99.8 % to 95.1 % with increasing SiC volume fraction between 55 % and 65 %, that of the bimodal composite was higher than 97 % in a SiC volume fraction range up to 70 %. The thermal conductivity of the bimodal composite was higher than that of the monomodal composite in a SiC volume fraction range higher than 60 %. The coefficient of thermal expansion of the composites falls in the upper line of Kerner's model, indicating strong bonding between the SiC particle and the Al matrix in the composite.

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The effects of B content and the heat treatment on the properties of gas atomized powders with Ni - 22 mass% Cr - X mass% Mo - Y mass% B compositions ((X, Y) = (23, 1.0), (26, 1.6), (30, 2.1), (33, 2.6)) were investigated. The powders were produced by gas atomization, followed by sieving under 150 µm in the particle size. Then the powders were heat treated at various temperatures to investigate the effects of the temperatures.
As a result, the powders with less than 1.6 % B before the heat treatment consisted of only Ni - based supersaturated solid solution with B. On the other hand, in the powders with more than 2.1 % B before the heat treatment, not only Ni - based matrix but also coarse complex boride were observed. Tetragonal M₃B₂ type complex boride precipitated in all powders after the heat treatment at more than 1073 K. Furthermore, all examined powders after the heat treatment at 1473 K had almost the same matrix composition as Ni - 22 mass% Cr - 16 mass% Mo. Vickers hardness of these powders increased with increasing B content.

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The high – and low-temperature relaxations in Zr – based bulk metallic glasses (BMGs) were investigated in terms of volume relaxation. Both relaxations exhibited the decrease of volume during the relaxation, and their behaviors were well described with a stretched exponential relaxation function. The kinetics of high-temperature relaxation was represented by a Vogel-Fulcher-Tammann equation for the relaxation time and by Kohlrausch indices linearly increased with temperature. On the other hand, the kinetics of low-temperature relaxation for respective Zr₅₅Cu₃₀Ni₅Al₁₀ BMG was characterized by an Arrhenius type temperature dependence of the relaxation time, and by almost constant value of Kohlrausch index. Consequently, the high – and low-temperature relaxations were regarded as α – relaxation and slow β – relaxation reported for dynamical measurements of the structural relaxation, respectively.

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Since metallic glasses do not require so rapid cooling in their formation as conventional amorphous materials do, they have fewer restrictions in manufacturing processes and product dimensions. The metallic glasses are more promising materials for industrial production and applications.
Gas atomization process seems to be suitable for the mass production of metallic glass powders, where the cooling rate during solidification is much higher than that of conventional casting, although it is lower than that required by melt-spun amorphous ribbons.
Fe – based and Ni – based alloys were chosen from the viewpoint of industrial applications. Feasibility of the application of gas atomization for their glass powder production and subsequent consolidation processes were discussed in this paper.

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Dynamic relaxation of Pd_42.5Ni_7.5Cu₃₀P₂₀ metallic glass (T_g～575 K) was measured in T = 153～563 K (27～98 % of T_g) with the angular frequency (ω) = 10⁻³～10² rad/s under the isothermal condition. By the time - temperature superimpose rule, master curves for storage (E'and loss (E'') moduli in the angular-frequency range with 16 orders of magnitude were successfully obtained. In addition to the α - relaxation and slow β - relaxation, which have been discusses in literatures, the present master curves exhibits another relaxation mode in the lower temperature region (< RT) with activation energy Q = 0.25 eV which is the fastest among three. These dynamic relaxations were characterized with the typical stretched exponent relaxation function, then, the processes for these relaxations were discussed thermodynamically from the activation energy and the attempt frequency.

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A study for amorphous alloys with high elongation and high corrosion resistance for thermal spray coating was carried out on Ni - based alloys. The corrosion weight loss of as spun Ni - Mo - B ternary alloy shows the very low value less than 0.5 mass%/day. The corrosion weight loss of quenched Ni₆₆Mo₁₅B₁₉ alloy is not dependent on quenching rate of the samples. The sprayed Ni₆₆Mo₁₅B₁₉ alloy has 5 times as corrosion resistance as hastelloy and exhibits same hardness as sprayed Fe₄₅Cr₃₅P₁₃C₇ alloy on commercial and Cermet. From these results, thermal sprayed Ni - Mo - B alloy is expected as combined coating with high wear resistance and high corrosion resistance.

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About the paper by Yasushi SUGAWARA et al. published in the February 2013 issue of the Journal, the authors requested that author's name in the original paper should be corrected.

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About the paper by Kenji Date et al. published in the March 2013 issue of the Journal, the authors requested that some errors in the original paper should be corrected.

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