Pd基金属ガラスの電子構造と相安定性

概要

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Stability of the Pd40Ni40P20 bulk metallic glass (BMG) was investigated by making full use of its relevant crystals which possess the same local atomic arrangements (trigonal prism cluster) about phosphorus as those in the BMG. The electronic structure of relevant crystals calculated by the FLAPW band calculation showed covalent bonds between phosphorus and transition metal elements (nickel and palladium). This covalent bonds must lead to a low internal energy of the relevant crystals, and perhaps of the corresponding metallic glass. Characteristics in the density of states were well reproduced in the cluster orbitals of the (Pd, Ni)9P trigonal cluster calculated by the DV-Xα method. This fact indicates that the electronic structure of the relevant crystals is dominated by that of the trigonal cluster. Photoemission spectroscopy on the relevant crystals and the BMG proved that all these phases possess nearly the same electronic structure. It is concluded that the structure of BMG is built up with the random network of the (Pd, Ni)9P clusters with large degree of flexibility with keeping the low internal energy. This condition must lead to a decrease of free energy of the system and stabilize the BMG.
社団法人粉体粉末冶金協会の論文
2007-11-15