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Pile-Up Based Hall-Petch Considerations at Ultra-Fine Grain Sizes

Published online by Cambridge University Press:  15 February 2011

T. R. Smith ,
R. W. Armstrong ,
P. M. Hazzledinew ,
R. A. Masumura  and
C. S. Pande
T. R. Smith
Affiliation:
Materials and Nuclear Engineering Department
R. W. Armstrong
Affiliation:
Department of Mechanical Engineering, University of Maryland, College Park, MD 20742
P. M. Hazzledinew
Affiliation:
UES Inc., 4401 Dayton-Xenia Road, Dayton OH 45432
R. A. Masumura
Affiliation:
Naval Research Laboratory, Washington DC 20375-5343
C. S. Pande
Affiliation:
Naval Research Laboratory, Washington DC 20375-5343
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Abstract

The dislocation pile-up explanation for the Hall-Petch (H-P) relation is re-examined for ultrafine grain sizes when only a few dislocations are involved in the pile-up, formed necessarily at applied stress levels near to the theoretical limit. Each dislocation added to the pile-up produces a step reduction in the H-P stress. Consequently, differences in dislocation configurations and types of pile-ups are easily recognized in the limit of small dislocation numbers. A significant reduction occurs in the H-P slope value (i.e., microstructural stress intensity) for the extreme case of only one dislocation loop being expanded against the grain boundary obstacle stress.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 362: Symposium J – Grain-Size and Mechanical Properties--Fundamentals and Applications , 1994 , 31
Copyright
Copyright © Materials Research Society 1995

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