Papers by Keyword: Glassy Alloys

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Authors: Masashi Hasegawa, Tsunehiro Takeuchi, Kazuo Soda, Hirokazu Sato, Uichiro Mizutani
Abstract: The electronic structure and phase stability of the Zr-Ni-Al ternary glassy alloys, have been systematically investigated experimentally and theoretically. Thermal stability and crystallization process have been clarified by the DSC and XRD measurements. Composition dependence of the stability parameter; Tg/Tl has been clarified. The electronic structure around the Fermi level has been investigated by using the high resolution UPS. It is found that there is a sizable pseudogap at the Fermi level of the electronic structure of the Zr65Ni20Al15 glassy alloy. The DVXα calculations for the charateristic clusters in the Zr-Ni-Al glassy alloy having high glass forming ability have been also performed. It is found that these clusters formation reduces the internal energy and can contribute to the phase stability. The LMTO-ASA band calculations for the Zr6NiAl2 compound which is the most relevant compound to the Zr60Ni25Al15 glassy alloy have been also performed. It is found that there is a sizable pseudogap at the Fermi level in its electronic structure, suggesting exiting of the pseudogap of the glassy alloy.
Authors: M.F. de Oliveira, J.E. May, Walter José Botta Filho, Claudemiro Bolfarini, Claudio Shyinti Kiminami
Authors: Lj. Ouyang, Dmitri V. Louzguine-Luzgin, Hisamichi Kimura, T. Ohsuna, Srinivasa Ranganathan, Akihisa Inoue
Authors: Masuyuki Hasegawa, M. Takeuchi, D. Nagata, T. Wada, Hidemi Kato, Y. Yamaura, Akihisa Inoue
Abstract: The hydrogen-induced internal friction and mechanical strength of the Ti-rich Ti34Zr11Cu47Ni8 and (Ti34Zr11Cu47Ni8)98Si2 hydrogenated glassy alloys have been investigated. It is found that the tensile strength is more than 0.8 GPa at room temperature when the hydrogen content is below about 20 at% for both alloys. The frequency dependence of peak temperature of the hydrogen-induced internal friction of (Ti34Zr11Cu47Ni8)98Si2-17.3 at%H hydrogenated glassy alloys has been clarified. Activation energy and pre-exponential factor are estimated to be 0.35 eV and 1.3x10-12, respectively. Compared with these values with those of Zr40Cu49Al10Si1 hydrogenated glassy alloys which show an internal friction peak around 300 K at about 300 Hz, it is found that the activation energy is much smaller than that of the latter although the pre-exponential factor is almost the same. Considering their similar composition and different component (Al), it is suggested that the component Al of the latter glassy alloys is effective for the higher activation energy which results in the increase of the peak temperature.
Authors: Antal Lovas, E. Kisdi-Koszó, L.K. Varga, Jenő Kovác
Authors: Mikio Fukuhara, Wei Zhang, Dmitri V. Louzguine-Luzgin, Akihisa Inoue
Abstract: Using ultrasonics, acoustic characteristics of Pd40Cu30P20, Zr55Cu30Al10Ni5, Zr65Pd12.5Ni10Al7.5 Cu5, Cu55Zr30Ti10Pd5, Cu45Zr20Hf25Ag10 and Ti41.5Cu42.5Ni7.5Hf5Zr2.5Sn1 glassy alloys were examined in terms of complex elasticity. The order of bulk modulus (K), Lamè parameter (λ ), Young (E ) and shear (G ) moduli of the glassy alloys is monopoltical character of glassy alloys, except for polymers and rubbers. For metals and alloys, ceramics, polymers and glassy alloys, Poison’s ratio correlates well to ratio G /K. Complex elasticity indicates that viscoelasticity of the glassy alloys is predominated by volumetric motion.
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