Comparative study of local structure in Zr_(70)Al_(10)Ni_(20) and quasi-crystal-forming Zr_(70)Al_9Ni_(20)Pd_1 metallic glasses

摘要

The local structure of Zr_(70)Al_9Ni_(20)Pd_1 metallic glass, in which a nano-icosahedral quasi-crystalline phase (I-phase) is formed in the primary stage of crystallization, has been examined and compared with that of Zr_(70)Al_(10)Ni_(20), the supercooled liquid state of which has a high stability. Since the local environments around the Zr and Ni atoms do not change drastically by the addition of 1 at. percent Pd to Zr_(70)Al_(10)Ni_(20), as evidenced by radial distribution function (RDF) and extended x-ray absorption fine structure (EXAFS) studies, we deduce that the icosahedral phase formed in the Zr_(70)Al_9Ni_(20)Pd_1 metallic glass has a local structure similar to that in Zr_(70)Al_(10)Ni_(20)- Although a very slight rearrangement of Zr-Zr atomic pairs occurs during quasi-crystallization. the I-phase formation is achieved without disturbing the dominant local structure in the glassy state of the Zr_(70)Al_9Ni_(20)Pd_1. An icosahedral local structure is proposed for Zr-Al-Ni metallic glass system as well as for primary quasi-crystal (QC)-forming Zr-based metallic glasses.