Nanoicosahedral quasicrystalline phase in Zr-Pd and Zr-Pt binary alloys

Citation
J. Saida et al., Nanoicosahedral quasicrystalline phase in Zr-Pd and Zr-Pt binary alloys, J APPL PHYS, 90(9), 2001, pp. 4717-4724
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF APPLIED PHYSICS
ISSN journal
0021-8979 → ACNP
Volume
90
Issue
9
Year of publication
2001
Pages
4717 - 4724
Database
ISI
SICI code
0021-8979(20011101)90:9<4717:NQPIZA>2.0.ZU;2-Z
Abstract
It is found that a nanoicosahedral phase in the diameter less than 20 nm is formed as a primary crystalline phase in the melt-spun Zr70Pd30 and Zr80Pt 20 binary amorphous alloys. The nanoicosahedral phase is also formed in the as-quenched state in the Zr80Pt20 binary alloy by controlling the quenchin g rate. The slight redistribution of approximately 3 at % is observed durin g the quasicrystallization in the Zr70Pd30 alloy. In contrast, no significa nt compositional change between the nanoicosahedral and residual amorphous phases is observed in the Zr80Pt20 alloy. It is suggested that the precipit ation of nanoicosahedral phase in the Zr70Pd30 alloy takes place by a diffu sion-controlled growth mode accompanying an increase in nucleation rate. Th e activation energy for grain growth is calculated to be 270 kJ mol(-1), wh ich implies the growth of icosahedral phase without a long-range atomic red istribution. The icosahedral medium-range order in the diameter range less than similar to2 nm is observed in the high-resolution electron micrographs of the melt-spun Zr70Pd30 and Zr80Pt20 amorphous alloys. It is realized th at the icosahedral quasicrystalline phase can grow easily with assimilating the icosahedral medium-range order due to a slight redistribution of const itutional elements during quasicrystallization. The formation of the nanoic osahedral phase in the Zr70Pd30 and Zr80Pt20 binary alloys appears to be at tributed to the existence of the icosahedral medium-range order in the amor phous and/or liquid states. (C) 2001 American Institute of Physics.