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Correia, J, B.*; Livramento, V.*; Shohoji, Nobumitsu*; Tresso, E.*; Yamamoto, Kazunori; Taguchi, Tomitsugu; Hanada, Kotaro*; Osawa, Eiji*
Materials Science Forum, 587-588, p.443 - 447, 2008/00
Nanostructured metals and nanocomposites are ways to address the low hardness problem, provided the nanostructured material is thermally stable during processing and service. In the present research, Cu composite powders, with 5 to 30 at % nanodiamond, were consolidated into bulk samples. The copper-nanodiamond composite powders were vacuum encapsulated and extruded at 600 
C. A significant proportion of the initial hardness in the powders is retained after extrusion. Transmission electron microscopy of the extruded material indicates good bonding between the nanodiamond particles and the copper matrix. Raman spectroscopy on the consolidated samples evidences the presence of graphite, possibly due to partial disintegration of ultradisperse nanodiamond agglomerates.
Yamamoto, Kazunori; Taguchi, Tomitsugu; Hanada, Kotaro*; Osawa, Eiji*; Inakuma, Masayasu*; Livramento, V.*; Correia, J, B.*; Shohoji, Nobumitsu*
Diamond and Related Materials, 16(12), p.2058 - 2062, 2007/12
Times Cited Count：6 Percentile：31.31(Materials Science, Multidisciplinary)Nano-sized polymorphs of carbon continue to attract much attention of scientists and provide new targets of examination with transmission electron microscope (TEM). We present here TEM images of a number of nanocarbons which played critical roles in some stage of their R&D, such as mechanical alloying of Cu and nanodiamond, diamond from soot, and short carbon nanocylinders by milling with microbeads. Emphasis is placed on nanodiamonds.
Hanada, Kotaro*; Yamamoto, Kazunori; Taguchi, Tomitsugu; Osawa, Eiji*; Inakuma, Masayasu*; Livramento, V.*; Correia, J, B.*; Shohoji, Nobumitsu*
Diamond and Related Materials, 16(12), p.2054 - 2057, 2007/12
Times Cited Count：26 Percentile：70.43(Materials Science, Multidisciplinary)This paper describes the microstructures and mechanical properties of Cu nanocomposites containing 0-30 at% diamond nanoparticles. The Cu nanocomposite powders are fabricated by mechanical milling method and are consolidated by spark plasma sintering and hot extrusion. Microstructural observation shows that the homogeneous distribution of diamond nanoparticles in the Cu nanocomposite can be achieved by extrusion with large plastic deformation, in spite of 20 at% diamond content, and that the nanocomposite with homogeneous distribution of diamond nanoparticles has ultra-fine grain structure, approximately 50 nm. Vickers hardness and compression tests on the SPS-consolidated and hot-extruded samples show that the detonation nanodiamond dispersed homogeneously in the Cu matrix enhances the mechanical properties.
Yamamoto, Kazunori; Taguchi, Tomitsugu; Hanada, Kotaro*; Inakuma, Masayasu*; Osawa, Eiji*; Shohoji, Nobumitsu*; Livramento, V.*; Correia, J, B.*
no journal, ,
This presentation describes the nano-structures of Cu nanocomposites containing 20 and 30 at% diamond nanoparticles. The Cu nanocomposite powders were fabricated by mechanical milling method and were consolidated by hot extrusion. The solidified samples were thinned to prepare the specimens by focused ion beam technique, and the specimens were examined by TEM and EDS. The micro-structural observation showed that the homogeneous distribution of diamond nanoparticles in the Cu nanocomposite could be achieved in 20 at% diamond content, and that the nanocomposite with homogeneous distribution of diamond nanoparticles has ultra-fine grain structure of approximately 50 nm in diameter.
Serizawa, Hiroyuki; Osawa, Takahito; Oishi, Yuji*; Nemoto, Yoshiyuki; Kondo, Keietsu; Shohoji, Nobumitsu*; Kaji, Yoshiyuki
no journal, ,
A new reaction model for evaluating the activity of oxygen and hydrogen atoms of H
O molecules is proposed. The surprisingly high value of the activity implies that the production process of volatile metal hydroxides might be reconsidered.
