Structural relaxation and plastic flow in amorphous La50Al25Ni25

Citation
B. Van Aken et al., Structural relaxation and plastic flow in amorphous La50Al25Ni25, MAT SCI E A, 278(1-2), 2000, pp. 247-254
Citations number
18
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
ISSN journal
09215093 → ACNP
Volume
278
Issue
1-2
Year of publication
2000
Pages
247 - 254
Database
ISI
SICI code
0921-5093(20000215)278:1-2<247:SRAPFI>2.0.ZU;2-U
Abstract
The tensile deformation of amorphous La50Al25Ni25 is studied in an extensi ve set of tensile tests at temperatures just below the glass transition tem perature. Depending on the pre-annealing treatment, in many cases strain so ftening occurs during the tensile tests. Only in the case of a very short p re-annealing treatment does apparent strain hardening occur. After deformat ion, up to epsilon = 0.3, all samples are tested by differential scanning c alorimetry, which reveals that the glass transition peak depends on the tem perature and strain rate during the tensile test, but not on the pre-anneal ing treatment. The entire set of experimental evidence can adequately be ex plained by the free volume concept. The conclusion is that during plastic d eformation additional free volume is created as compared with thermal equil ibrium, and the structure reaches a temperature and strain rate dependent s teady state of disorder, i.e. amount of free volume. A quantitative descrip tion of this process, which should be envisaged as the production of a smal l amount of free volume during each flow event, is presented. (C) 2000 Else vier Science S.A. All rights reserved.