Maaß, R. and Uchic, M. D. (2012) In-situ characterization of the dislocation-structure evolution in Ni micro-pillars. Acta Materialia, 60 (3). pp. 1027-1037. ISSN 1359-6454 http://resolver.caltech.edu/CaltechAUTHORS:20120405-085142701
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The high strength of micro-crystals is determined in the early flow regime, where a transition from elastic to plastic flow is obscured if compared to stress–strain data from bulk single crystals. In the present work we therefore focus on the evolution of dislocation structures in Ni micro-pillars during early deformation by employing in-situ Laue micro-diffraction. It will be shown that substantial changes in the lattice fine structure, such as multiple subgrain formation and significant rotational gradients, can be resolved prior to the onset of large strain generation. The results reveal more pronounced effects for smaller sample dimensions and also suggest that most of the evolving dislocation structure is formed prior to the occurrence of large strain bursts. A clear increase in dislocation density as a function of strain is observed, which we discuss in the context of size-dependent strain hardening and exhaustion hardening.
|Additional Information:||© 2011 Acta Materialia Inc. Published by Elsevier Ltd. Received 1 July 2011. Revised 2 November 2011. Accepted 4 November 2011. Available online 15 December 2011. R.M. gratefully acknowledges the splendid support of the MicroXAS beamline crew at the Swiss Light Source: D. Grolimund, C. Borca, and M. Willimann. Thanks go also to the Materials Science and Simulation group at the Paul Scherrer Institute: H. Van Swygenhoven, S. Van Petegem, J. Zimmermann, Stefan Brandstetter and Christian Brandl. Further, R.M. would like to acknowledge the support of Hysitron Inc. for technical support of the MCD-development. Gratitude is expressed towards P.M. Derlet and C.P. Frick for valuable discussions. R.M. also thanks the Alexander von Humboldt foundation for financial support at his current affiliation.|
|Subject Keywords:||Micro-compression; Plastic deformation; Strain gradient; Single crystal; Strain hardening|
|Official Citation:||R. Maaß, M.D. Uchic, In-situ characterization of the dislocation-structure evolution in Ni micro-pillars, Acta Materialia, Volume 60, Issue 3, February 2012, Pages 1027-1037, ISSN 1359-6454, 10.1016/j.actamat.2011.11.007.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||10 Apr 2012 21:57|
|Last Modified:||10 Apr 2012 21:57|
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