A model for direct and inverse Hall-Petch relation for nanocrystalline ceramics

•Grain boundary sliding violates Hall-Petch dependences for nanocrystalline ceramics.•Its activation energy can depend on the temperature regime of synthesis of ceramics.•High activation energy leads to direct Hall-Petch dependences.•Low activation energy results in inverse Hall-Petch dependences. A...

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Bibliographic Details
Published in:Materials letters Vol. 260; p. 126886
Main Authors: Sheinerman, Alexander G., Castro, Ricardo H.R., Gutkin, Mikhail Yu
Format: Journal Article
Language:English
Published: Amsterdam Elsevier B.V 01.02.2020
Elsevier BV
Subjects:
Ceramics
Grain boundaries
Hall-Petch effect
Hardness
Materials science
Micromechanical modeling
Nanocrystals
Plastic deformation
Sliding
Ceramics
Hall-Petch effect
Hardness
Micromechanical modeling
ISSN:0167-577X, 1873-4979
Online Access:Get full text
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Summary:•Grain boundary sliding violates Hall-Petch dependences for nanocrystalline ceramics.•Its activation energy can depend on the temperature regime of synthesis of ceramics.•High activation energy leads to direct Hall-Petch dependences.•Low activation energy results in inverse Hall-Petch dependences. A model describing both direct and inverse Hall-Petch dependences observed in nanocrystalline ceramic MgAl2O4 spinel is proposed. Within the model, plastic deformation in nanocrystalline ceramics (NCCs) is realized via lattice dislocation slip combined with thermally activated grain boundary (GB) sliding. The model strongly suggests that the controlling parameter determining the type (direct or inverse) of the Hall-Petch dependence is the GB sliding activation energy. It is assumed that this quantity can be affected by the temperature regime of NCC synthesis and therefore rationalize conflicting data reported in the literature concerning the onset of the inverse Hall-Petch behavior in this system.
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ISSN:0167-577X
1873-4979
DOI:10.1016/j.matlet.2019.126886