Hydrogen-doped Bulk Metallic Glasses as High Damping Material
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Hydrogen-doped Bulk Metallic Glasses as High Damping Material Teruaki Yagi, Rikiya Oguro, Ryuji Tamura and Shin Takeuchi Department of Materials Science and Technology, Science University of Tokyo, Noda, Chiba 278-8510, Japan ABSTRACT Bulk metallic glasses have extremely high strength and high ductility and are quite useful as the structural material. Many of bulk metallic glasses are based on Zr, Ti and Pd; these elements have a high affinity with hydrogen and hence the bulk metallic glasses can contain a large amount of hydrogen atoms. It is known that hydrogenized amorphous metals, as well as hydrogenized metallic crystals, exhibit Snoek-type relaxation, and hence metallic glasses containing a high density of hydrogen can have a high internal friction. In the present experiments, internal friction measurements have been performed for bulk metallic glasses doped with a variety of hydrogen concentrations. It is shown that the peak -2 value of the internal friction reaches the order of 10 in Zr-based bulk metallic glasses which have the fracture strength as high as 1.5 GPa. Thus, hydrogen-doped bulk metallic glasses can be used as the high-strength, high-damping material. INTRODUCTION Demands for high-damping materials are increasing in the modern society for various purposes: the fine machinery, the antivibrating system, the suppression of resonance for safety operation of high speed machines, the suppression of noise, etc. A variety of alloys have so for been developed as the high-damping material. The mechanism of the high damping is due to an internal friction either by the dislocation glide, the twin boundary migration, the martensitic transformation or the magnetic domain wall motion. In general, the harder the material the lower the damping coefficient as a natural consequence of the fact that the damping is in most cases due to micro-plastic deformation. In figure 1, we plot the specific damping capacities (SDC) of materials as a function of the tensile strength of the materials; the SDC is defined by the energy loss per one cycle of vibration and is related to the internal friction Q-1 by SDC§2πQ-1. As seen in the figure, the same kind of material, e.g. steels, has the negative correlation between the SDC and the tensile strength. In the figure, the developed high-damping materials having the SDC larger than 20 % are plotted by solid marks. It is found that these materials exhibit also the above negative correlation and that no high-damping material has the tensile strength higher than 1 GPa. Although metallic glasses were long known to possess extremely high strength and toughness since 1970’s, until the late 1980’s metallic glasses had been produced only as a thin L11.10.1
Specific Damping Capacity (%)
100
10
MCM (Mg-Cu-Mn) K1X1 (Mg-Zr) Silentalloy Fe-Cr-Al-C(f.+m., Trancalloy) 6N PTFE Mg (Fe-Cr-Al) Mn-Cu Gentalloy(Fe-Co) Cu-Al-Ni Nobinite (Inver Cast Iron) Mg-Si Ti-Ni PE Al-78%Zn Al-Zn Sonostone(Mn-Cu-Al) PP R.F.C. SUS304HD grey cast iron Ni Incramute(Cu-Mn-Al) (high C. austen.) Pb Fe ABS PA FC100 A
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