Papers by Author: Hiroyasu Tezuka

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Authors: Hyun Bom Lee, Hiroyasu Tezuka, Equo Kobayashi, Tatsuo Sato, Kee Do Woo
Abstract: A planetary ball milling (PBM) technique was employed to fabricate mechanically alloyed (MA processed) Al-Nb2O5 composite powder. Nano or sub-micron sized Nb2O5 particles were homogeneously embedded in the Al particles after milling for various periods. None of cracks, by-products and pores were observed in the areas between embedded Nb2O5 particulates and Al matrix powder after milling. The sequence of the in-situ reaction was confirmed by DSC, XRD measurements, optical microscopy and EPMA. The specific temperature of the in-situ reaction was between 650 and 700°C. Al-based metal matrix composites (MMC) reinforced with the sub-sieve sized θ-Al2O3 particulates and Al3Nb intermetallic compound were successfully fabricated by the in-situ reaction process. The substituted Nb by the in-situ reaction was fully reacted with Al to form the Al3Nb intermetallic compound during sintering. A number of sub-sieve sized θ-Al2O3 particulates and Al3Nb intermetallic compound formed by the in-situ reaction between Al and Nb2O5 were homogeneously distributed in the Al matrix during sintering. Nano sized θ-Al2O3 particulates are preferentially distributed near the Al3Nb intermetallic compound and no by-products are formed in the interfaces with the Al matrix.
Authors: Kenichi Yaguchi, Hiroyasu Tezuka, Tatsuo Sato, Akihiko Kamio
Authors: Ken Moizumi, Kenichiro Mine, Hiroyasu Tezuka, Tatsuo Sato
Authors: Takaya Suzuki, Y. Ishii, A. Itami, Kohsaku Ushioda, Naoki Yoshinaga, Hiroyasu Tezuka
Authors: Sung Kil Hong, S.H. Hwang, J.C. Choe, Ik Min Park, Hiroyasu Tezuka, T. Sato, T. Kamino
Authors: Rodinei M. Gomes, Tatsuo Sato, Hiroyasu Tezuka, Akihiko Kamio
Authors: W. Eidhed, Chaowalit Limmaneevichitr, Hiroyasu Tezuka, Tatsuo Sato
Abstract: Al-Mg-Si based alloys have been developed to produce an advanced feedstock material for thixoforming. Effects of excess Si, Mn addition and deformation on microstructure evolutions during reheating and partial remelting were studied. The homogenized microstructures of the Mnadded Al-Mg-Si alloys consist of the Al12Mn3Si2 intermetallic compound along grain boundaries of equiaxed grains with fine-spherical and needle-like morphologies. The deformation by cold-rolling has a strong effect on the semi-solid microstructures of the Mn-added Al-Mg-Si alloys compared with the balanced and excess Si alloys. The Mn-added Al-Mg-Si alloys exhibit good features to produce the feedstock material for thixoforming.
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