title: Microstructure of fragile metallic glasses inferred from ultrasound-accelerated crystallization in Pd-based metallic glasses.
abstract: By utilizing ultrasonic annealing at a temperature below (or near) the glass transition temperature Tg, we revealed a microstructural pattern of a partially crystallized Pd-based metallic glass with a high-resolution electron microscopy. On the basis of the observed microstructure, we inferred a plausible microstructural model of fragile metallic glasses composed of strongly bonded regions surrounded by weakly bonded regions (WBRs). The crystallization in WBRs at such a low temperature under the ultrasonic vibrations is caused by accumulation of atomic jumps associated with the beta relaxation being resonant with the ultrasonic strains. This microstructural model successfully illustrates a marked increase of elasticity after crystallization with a small density change and a correlation between the fragility of the liquid and the Poisson ratio of the solid.
authors.affiliation: Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501, Japan. tichi@mtl.kyoto-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Ichitsubo
authors.forename: E
authors.initials: E
authors.lastname: Matsubara
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: H S
authors.initials: HS
authors.lastname: Chen
authors.forename: N
authors.initials: N
authors.lastname: Nishiyama
authors.forename: J
authors.initials: J
authors.lastname: Saida
authors.forename: K
authors.initials: K
authors.lastname: Anazawa