THERMAL-ACTIVATION ANALYSIS OF DISLOCATIONS IN OBSTACLE FIELDS

Citation
V. Mohles et D. Ronnpagel, THERMAL-ACTIVATION ANALYSIS OF DISLOCATIONS IN OBSTACLE FIELDS, Computational materials science, 7(1-2), 1996, pp. 98-102
Citations number
5
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science
ISSN journal
0927-0256
Volume
7
Issue
1-2
Year of publication
1996
Pages
98 - 102
Database
ISI
SICI code
0927-0256(1996)7:1-2<98:TAODIO>2.0.ZU;2-R
Abstract
The strength of metals as a function of temperature is still not very well understood, even in the case where thermal overcoming of obstacle s by dislocations is believed not to be superimposed by other temperat ure dependent effects? like solute atom diffusion. Our simulation calc ulations offer a means to close some of the gaps in understanding, as they exclude both superimposed effects of any kind as well as errors d ue to non-ideal experimental conditions. In this contribution our resu lts concerning the activation enthalpy and -volume for obstacles of at omic size are presented, The simulations reveal that for equivalent co nditions an obstacle field can well be compared to an equidistant obst acle arrangement to be overcome. Another simplification of the activat ion model can be done by replacing this obstacle row by a continuous o bstacle wall without affecting the activation parameters. From this it has to be concluded that the activation volume does not always depend on the obstacle spacing due to first principles. A length L is introd uced which for a concrete obstacle spacing determines the number of ob stacles to be overcome simultaneously for thermal activation. Calculat ions on obstacle fields show that for solute atom concentrations betwe en 0.1% and 20%, this length L rather than the obstacle spacing contro ls thermal activation.