メカニカルアロイングによる2相分離型Cu-V系のアモルファス化とその原子構造

概要

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Cu and V atoms are immiscible even in the liquid state and its alloy system is characterized by a positive heat of mixing. The mixture of elemental Cu and V powders was compulsively mixed by mecahnical alloying(MA). The mixing at an atomic level and amorphization process during MA were studied by neutron diffraction and DSC measurements.<BR>A sharp peak characteristic of the crystallization of an amorphous phase is not observed in the DSC spectrum even after 120 hours of milling. However, the total energy stored be MA process increased with MA time and the value after 120 hours of milling tended to saturate at 14.3 kJ/mol.<BR>Some of Bragg peaks of fcc-Cu crystal observed in S(Q) before MA quickly diminish and others become broadened with increasing milling time. A halo pattern dominates after 60 hours milling, though the 1st peak remains rather sharp in comparison with that of a typical amorphous alloy. The distribution peaks of fcc-Cu crytal in RDF(r) broaden and approach gradually to those<BR>characteristic of an amorphous state. Especially, the peaks of 2nd and 5th Cu-Cu neighbor positions observed within 7 A distance drastically decrease and eventually disappear.<BR>These results may mean that the amorphization of Cu-V powders by MA gradually but eventually proceeds.
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