東北大学 · 工学
D. V. Louzguine教授の研究室では、金属ガラスおよび非晶質合金のナノデビトリフィケーション現象に注目し、ナノスケールの結晶性または準結晶相の形成がもたらす力学的特性の向上を解明しています。特に、Cu基やAl基の金属ガラス系において、相分離や析出が強度と延性の両立に寄与するメカニズムをX線回折や走査型電子顕微鏡を用いて詳細に解析しています。また、冷却履歴や元素の電負う度がガラス形成性や力学的安定性に与える影響についても、差熱走査量熱測定を応用した理論的・実験的アプローチを展開しています。
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This overview paper summarizes a large number of data connected with nano-devitrification of metallic glassy and amorphous alloys on heating which form nanoscale crystalline or quasicrystalline particles. In some alloys this effect leads to formation of the nanocomposites with enhanced mechanical properties compared to fully glassy and crystalline alloys.
This article summarizes the general structural features and important properties of quasicrystals, a relatively new class of materials belonging to solid-state substances. Quasicrystals, which have a long-range quasiperiodic order but no three-dimensional translational periodicity, are structurally different from both conventional crystals and glassy solids. Although applications are still highly limited, quasicrystals are attracting significant attention as a structual constituent of mixed-phas
Low ductility of glassy alloys prevents their technical application as structural materials. In this work, we study the Cu-based crystal-glassy composite material with good mechanical properties. Formation of the Cu10Zr7 phase in the glassy matrix of a high-strength Cu50Zr30Ti10Nb10 bulk alloy upon solidification led to higher Young’s modulus and enhanced ductility of such a composite compared to Cu-based glassy alloys. The as-cast structure was studied by x-ray diffraction and scanning electron
The letter describes influence of the electronegativity of the constituent rare-earth metals on the supercooled liquid region in the Al–(Gd, Dy or Er)–Ni–Co metallic glasses. The samples were studied by x-ray diffractometry and differential scanning calorimetry. Calorimetry data for the La and Sm—bearing glasses studied earlier were also taken in consideration for comparison. It is found that supercooled liquid range in the Al85RE8Ni5Co2 alloys strongly depends upon electronegativity of the RE m
The present letter shows how a continuous heating transformation diagram for a Cu60Hf25Ti15 metallic glass can be obtained by applying an extension of the Kissinger analysis. According to the calculation this glass is completely stable in the Earth’s climate for its lifetime. This extension of the Kissinger analysis method can be applied to any other metallic glass.
Metallic glasses demonstrate unique properties, including large elastic limit and high strength, which make them attractive for practical applications. Unlike crystalline alloys, metallic glasses, in general, do not exhibit a strain hardening effect, while plastic deformation at room temperature is localized in narrow shear bands. Room-temperature mechanical properties and deformation behavior of bulk metallic glassy samples and the crystal-glassy composites are reviewed in the present paper.
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