Internal stress superplasticity in anisotropic polycrystalline materials

Citation
K. Kitazono et al., Internal stress superplasticity in anisotropic polycrystalline materials, ACT MATER, 49(3), 2001, pp. 473-486
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
ACTA MATERIALIA
ISSN journal
1359-6454 → ACNP
Volume
49
Issue
3
Year of publication
2001
Pages
473 - 486
Database
ISI
SICI code
1359-6454(20010208)49:3<473:ISSIAP>2.0.ZU;2-X
Abstract
A theoretical model of internal stress superplasticity is developed in a si ngle-phase polycrystalline material with an anisotropic thermal expansion. Quasi-steady state creep equation during a thermal cycle is derived quantit atively based on continuum micromechanics. The model assumes that the gener ated mismatch strain is accommodated simultaneously by the plastic flow of the material. The linear creep deformation. which corresponds to internal s tress superplasticity, is obtained at low applied stress region. and the cr eep rate depends on the crystallographic texture of the material. The valid ity of the model is experimentally verified using polycrystalline zinc whic h is a typical metal having large anisotropy in thermal expansion. The calc ulated strain rates using the texture information and the isothermal creep equation agree quantitatively well with the experimental results. The appar ent activation energy of thermal cycling creep reveals 1/n (n: stress expon ent of isothermal creep) of that of isothermal creep, which is one of the c haracteristics of internal stress superplasticity. Except for the factors a ttributable to the material geometry, the thermal cycling creep equation in the polycrystalline material is identical to that in a metal matrix compos ite. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All r ights reserved.