Advanced Materials and Processing

Paper Title Page

Authors: L.M. Fang, Xiao Tao Zu
Abstract: Fe-doped SnO2 nanoparticles have been synthesized by a simple hydrothermal method. After Fe doping, the as-prepared SnO2 samples were calcined at different temperature from 350-800 °C in air for 1 h. The effects of Fe dopant and calcination on the microstructure and optical properties are investigated using X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM) , UV-VIS diffuse reflectance spectra (DRS). Results show that the Fe-doped SnO2 crystallites with the rutile phase was directly synthesized during hydrothermal process without calcination. A dramatically red shift in the absorbing band edge was observed with the decreasing crystallite size result from the increasing Fe content.
Authors: J.P. Wang, Wei Sun, Z. Zhang
Abstract: Crystalline approximants structurally related to decagonal quasicrystal in the as-cast and heat-treated Al75Pd15Fe10 alloys and defect structures in them have been studied by means of high-resolution electron microscopy (HREM). Structural defects of linear and planar types were found to exist extensively in the orthorhombic ε16-phase formed in the as-cast Al75Pd15Fe10 alloy. In contrast with the distribution and configuration of the defects in the as-cast ε16-phase, we found that high-temperature heat treatment promotes the formation of a kind of regular network of structural defects in the ε16-phase. This suggests that rearrangements of atom clusters and as well as defects occurred due to the heat treatment. The relationship between the distribution of atom clusters and the configuration of defects will be discussed.
Authors: Akari Fujii, Yoshihisa Kimoto, Shin Wakayama, Yorinobu Takigawa, Tokuteru Uesugi, Kenji Higashi
Abstract: Many studies have been conducted on mechanical properties in nanocrystalline Ni-W alloys. However, since these results are obtained in the specimens whose thickness is less than 100 μm and whose homogeneity is not strictly controlled, an inherent potential of the nanocrystalline Ni-W alloy may be hidden. Therefore, it is necessary to fabricate the bulk Ni-W alloy with sufficient thickness and homogeneity. In the present study, we develop novel electroforming process and fabricate the homogeneous nanocrystalline Ni-W alloys. The homogeneities of W-concentration in micrometer scale are confirmed by the W-concentration profiles obtained by the linear analyses of the energy dispersed spectroscopy (EDS). The single-phase nanocrystalline bulk Ni-W alloy with the thickness above 2 mm and minimized W-concentration gradient and fluctuation is featured for the first time.
Authors: Takuro Nakamura, Hiromoto Kitahara, Jung Goo Lee, Nobuhiro Tsuji
Abstract: Pure Al (99%) and pure Fe (99.5%) sheets were mutually stacked and severely deformed up to equivalent strain of 16 by the accumulative roll bonding (ARB) process in an attempt to achieve bulk mechanical alloying. The deformation was carried out at RT. The Al/Fe sheets ARB processed by 1 cycle showed a number of shear bands penetrating the stacked layers. The Fe layers, which were harder than the Al layers, were subdivided by the shear bands into diamond-shaped regions. Dissolution of Fe into Al was observed and a supersaturated solid solution was formed in the specimen ARB processed by 10 cycles. It was also found that local amorphization occurred at interface regions via formation of Al5Fe2 intermetallic compound.
Authors: Chang Seog Kang, Jae Ik Cho, C.Y. Jeong, Ik Hyun Oh, Jae Seol Lee, Joon Sik Park
Abstract: The mechanical properties of the nano-size primary α-Ti phase in Ti55Zr18Ni6Cu7Be14 bulk metallic glass (BMG) have been examined through various annealing temperatures and times. The yield strength and ductility were changed upon variation of α-Ti volume percent originate from heating conditions. The strength mechanism and associated heating conditions (heating rate, time and temperature) are discussed in terms of the microstructural observations and mechanical properties.
Authors: Hung Su Im, Sang M. Lee, Chan Gyu Lee, Bon Heun Koo, Jung Bum Yoon, Myung Hwa Jung
Abstract: We indicated synthesization of LCMO by hydrothermal reaction. The results of transmission electron microscopy revealed that the LCMO particles had wide range in size and various in shapes. The LCMO particles had a perovskite-type crystal structure with some other phases. Magnetic property was measured by physical property measurement system. Their crystallinity and magnetization tended to increased with increasing reaction time.
Authors: Kun Su Son, Xin Min Wang, Akihiro Makino, Akihisa Inoue
Abstract: Techniques for joint of materials are developed over 2000 years. The metallic liquid jointing technique which enables the joint of Ti41.5Cu42.5Ni7.5Hf5Zr2.5Si1 bulk glassy alloy without any crystallization is very useful to produce large bulk metallic glass. High velocity molten alloy streams are generated by ejection of alloy liquid through two nozzles at different sites. The jointed region has nearly the same structure, thermal stability and mechanical properties as those for the original glassy Ti41.5Cu42.5Ni7.5Hf5Zr2.5Si1 alloy.
Authors: Jin Cheng, Xiao Ping Zou, Fei Li, Hong Dan Zhang, Peng Fei Ren, Guang Zhu, Mao Fa Wang
Abstract: Y-shaped carbon nanowires as a multi-branched carbon nanostructure have potential applications in electrical nano-devices. In this paper, we report the synthesis of Y-shaped carbon nanowires obtained from ethanol flames. These Y-shaped carbon nanowires have different morphologies from one to another. It is interesting that there are two Y-junctions on individual carbon nanowires. According to our experimental results, the growth mechanism of Y-shaped carbon nanowires has been discussed and a possible growth model of these Y-shaped carbon nanowires has been proposed.
Authors: Bong Hwan Kim, Sang Mok Lee
Abstract: Al-Cu-Fe-B quasicrystalline and Mo coatings were obtained on the mild steel and brass substrates by thermal spraying routes for the purpose of replacement of Mo coatings with quasicrystalline ones. Quasicrystalline coatings were prepared by air plasma spraying and/or HVOF (High Velocity Oxygen Fuel) techniques followed by subsequent heat treatment, and Mo coatings, wire flame spraying. For comparative studies of important properties for industrial application, mechanical properties, bonding strength, surface energy, and tribological behavior were investigated based on microstructural characterization. Basic mechanical properties such as hardness, fracture toughness, and elastic modulus of quasicrystalline coating showed comparable values with those of Mo coatings. De-bonding tests of coatings deposited onto brass substrate indicated that the bonding strength of quasicrystalline coatings obtained by HVOF techniques exhibit higher value to Mo coatings. Non-sticking property analogized from surface energy calculation and friction coefficient of quasicrystalline coatings also showed better performance during the tests. It is suggested from this investigation that the quasicrystalline coating can be effectively used as a replacement of the Mo coating, which has shown a recent steep price rise and problems of accidental existence of minor environment harmful elements such as Cr6+, Pb, Cd, and Hg.
Authors: E.Z. Kim, Soo Ik Oh, Sang Mok Lee, C.Y. Yoon, Hoon Jae Park, Seung Soo Kim, Tae Hoon Choi, Kyoung Hoan Na
Abstract: Deformation characteristics and forming limit of ultrafine-grained bulk Al-Mg alloy were examined with upsetting process. The Al-7.5%Mg alloy produced by cryogenic milling and HIP was subjected to hot hydrostatic extrusion as a final consolidation in fabricating the ultrafine-grained bulk material. Upsetting was performed to study their mechanical characteristics in a practical forming process. The extruded specimen showed that the pores remained in spite of the HIP had been collapsed and almost eliminated. The effective removal of the distributed pores resulted in significant increase of formability by preventing early cracking. Metallographic investigations showed that the size of grain remained below a few hundred nanometer scale in the processes.

Showing 161 to 170 of 318 Paper Titles