Investigation of the stability of glassy state in the Zr- and Hf-based glassy alloys correlated with their transformation behavior

Citation
J. Saida et al., Investigation of the stability of glassy state in the Zr- and Hf-based glassy alloys correlated with their transformation behavior, J MATER RES, 16(12), 2001, pp. 3389-3401
Citations number
34
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
JOURNAL OF MATERIALS RESEARCH
ISSN journal
0884-2914 → ACNP
Volume
16
Issue
12
Year of publication
2001
Pages
3389 - 3401
Database
ISI
SICI code
0884-2914(200112)16:12<3389:IOTSOG>2.0.ZU;2-J
Abstract
The transformation behavior from glassy state was investigated in Zr- and H f-based glassy alloys. The primary phases are metastable face-centered-cubi c (fcc) Zr2Ni and fee Hf2Ni phases in the Zr65Al7.5Ni10Cu17.5 and Hf65Al7.5 Ni10Cu17.5 glassy alloys, respectively. By substitution of 5 at.% Pd for Cu , the primary phase changes to an icosahedral quasicrystalline phase in bot h alloys. It is found that the addition of elements, which have a positive or weak chemical affinity with one of the constitutional elements in the Zr -Al-Ni-Cu and Hf-Al-Ni-Cu glassy alloys, is effective for the precipitation of the icosahedral phase. It is suggested that Pd plays a dominant role in an increase in the number of nucleation sites. Since an icosahedron is con tained as a structure unit in the icosahedral, fee Zr2Ni and fee Hf2Ni phas es, it is implied that these phases are correlated with the local icosahedr al order. The high-resolution transmission electron microscopy images of th e as-spun Zr65Al7.5Ni10Cu7.5Pd10 and Hf65Al7.5Ni10Cu12.5Pd5 alloys reveal a possibility of the existence of the icosahedral ordered regions. It is the refore, concluded that the icosahedral short- or medium-range order exists and it stabilizes the glassy state in the Zr- and Hf-based multicomponent a lloys.