Phase transformations of ball-milled Nb50Zr10Al10Ni10Cu20 powders and the effect of annealing

Citation
Ms. El-eskandarany et al., Phase transformations of ball-milled Nb50Zr10Al10Ni10Cu20 powders and the effect of annealing, J ALLOY COM, 329(1-2), 2001, pp. 239-252
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF ALLOYS AND COMPOUNDS
ISSN journal
0925-8388 → ACNP
Volume
329
Issue
1-2
Year of publication
2001
Pages
239 - 252
Database
ISI
SICI code
0925-8388(20011114)329:1-2<239:PTOBNP>2.0.ZU;2-8
Abstract
A single amorphous phase of Nb50Zr10Al10Ni10Cu20 alloy owders was synthesiz ed by milling the elemental alloying powders in an argon atmosphere, using a planetary ball mill operated at a rotation speed of 2.1 s(-1). During the early and intermediate stages of milling (43-360 ks) the atoms for alloyin g elements of Zr, Al, Ni and Cu migrated and diffused into the Nb (base mat erial) lattice to form a supersaturated b.c.c. solid solution which transfo rmed into an amorphous phase with the same composition upon post-annealing at 725 K for 7.2 ks in an argon atmosphere differential scanning calorimete r (DSC) (thermally enhanced solid-state amorphization, TESSA). As the milli ng time increases (360-540 ks), the powders are subjected to continuous def ects and lattice imperfections that lead to a gradual change in the free en ergy so that the solid solution phase is transformed (mechanically enhanced solid-state amorphization, MESSA) to another metastable phase (amorphous). Towards the end of the milling processing time (720 ks), the b.c.c.-solid solution transformed completely into a single amorphous phase with the same composition. The crystallization temperature and the enthalpy change of cr ystallization for the obtained amorphous phase are 963 K and - 8.44 kJ mol( -1), respectively. (C) 2001 Elsevier Science BY All fights reserved.