Award Abstract #0237400
In-Situ TEM and SEM Studies of Fundamental Deformation and Failure Processes of Nano-Grained FCC Metals Using MEMS Stages

NSF Org:	DMR Division of Materials Research
Initial Amendment Date:	January 6, 2003
Latest Amendment Date:	May 9, 2007
Award Number:	0237400
Award Instrument:	Continuing grant
Program Manager:	Harsh Deep Chopra DMR Division of Materials Research MPS Directorate for Mathematical & Physical Sciences
Start Date:	February 1, 2003
Expires:	January 31, 2008 (Estimated)
Awarded Amount to Date:	$406000
Investigator(s):	Ian Robertson ianr@uiuc.edu (Principal Investigator) T. Saif (Co-Principal Investigator)
Sponsor:	University of Illinois at Urbana-Champaign SUITE A CHAMPAIGN, IL 61820 217/333-2187
NSF Program(s):	MMN
Field Application(s):	0106000 Materials Research
Program Reference Code(s):	AMPP,9251,9161
Program Element Code(s):	1771

ABSTRACT

This grant is on a study of the mechanical properties of nano-grained Cu, Al and Ni using MEMS stages with emphasis on in-situ testing to characterize the underlying deformation mechanisms that involve dislocation-dominated versus grain-boundary controlled as small grain sizes are approached. Another objective is to investigate the failure modes in nano-grained materials since dramatic changes are expected as the crack tip dimension becomes comparable to the grain or particle size. Understanding these processes at this length scale are important if reliable devices and new structural materials are to be constructed intelligently from these nanoscale building blocks. A major goal of the project is to use a novel microelectromechanical-based tensile test device that was designed and fabricated at the University of Illinois to measure the mechanical properties and to simultaneously observe the operative deformation and fracture process of two- and three-dimensional nanograin structures. The same device will be used in both the scanning and transmission electron microscopes, and thus it will be possible for the first time to directly correlate macroscopic mechanical properties with deformation and fracture processes in ultra-fine grained materials as a function of grain size. The aim is to investigate these aspects in FCC metals such as Cu, Al and Ni. In addition to the experimental studies, molecular dynamics simulations will be made to predict deformation mechanisms as grain size is reduced to nanometer size. The model predictions will be correlated with the experimental results.

The outcome of the proposed program will provide the foundation for developing new physical-based models for predicting the mechanical response of structures and devices containing nanosized grains and particles. The grant involves graduate student participation along with outreach program that has been in place at the University of Illinois.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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D. Follstaedt, K. Hattar, J. A. Knapp, Ian Robertson.  "In situ TEM investigation of abnormal grain growth in nanocrystalline Ni.,"  Fall MRS meeting. Symposium MM 2005.,  2005,  p. 0907-MM06.

David M. Follstaedt, Khalid Hattar, James A. Knapp and Ian M. Robertson.  "In Situ TEM Investigation of Abnormal Grain Growth in Nanocrystalline Nickel,"  Mater. Res. Soc. Symp. Proc.,  v.90,  2005,  p. 0907-MM06.

Hattar, K., D. M. Follstaedt, J. A. Knapp, I. M. Robertson.  "Defect structures created during abnormal grain growth in pulsed-laser deposited nickel,"  Acta Materialia,  v.56,  2008,  p. 794.

Hattar, K., M. J. Demkowicz, A. Misra, I. M. Robertson, R. G. Hoagland.  "Arrest of He bubble growth in Cu-Nb multilayer nanocomposites,"  Scripta Materialia,  v.58,  2008,  p. 541.

Ian Robertson, Taher Saif, Khalid Hattar and J. Han, Microscopy and Microanalysis Meeting, August 2006..  "Correlating dislocation behavior with macroscopic mechanical properties directly in the TEM through use of a novel tensile test device.,"  Microscopy and Microanalysis Meeting, August 2006.,  2006,  p. N\a.

J. A. Gregg; K. Hattar; C. H. Lei; I. M. Robertson.  "Mechanisms of Grain Growth in Free-Standing Nanograined Gold Thin Films,"  In-Situ Electron Microscopy of MaterialsMRS Proceedings Volume 907E,  v.907E,  2005,  p. 0907-MM06.

K. Hattar, J. Gregg, J. Han, T.Saif and I. M. Robertson.  "In situ TEM Observations of Grain Growth in Nanograined Thin Films - TROPHY AWARD PAPER,"  Stability and Thin Films and Nanostructures, MRS Fall 2004, 854E. http://www.mrs.org/publications/epubs/proceedings/fall2004/u/index.html.,  v.854E,  2004,  p. 6.6.1.

K. Hattar, J. H. Han, D. M. Follstaedt, S. J. Hearne, T. A. Saif, I. M. Robertson.  "Length Scale Effects on Deformation and Failure Mechanismsof Ultra-Fine Grained Aluminum,"  Mater. Res. Soc. Symp. Proc.,  v.907E,  2005,  p. 0907-MM01.

K. Hattar, J. Han, M. T. A Saif, I. M. Robertson.  "In situ transmission electron microscopy observations of toughening mechanisms in ultra-fine grained columnar aluminum thin films.,"  Journal of Materials Research,  v.20,  2005,  p. 1869.

K. Hattar, J.H. Han, D.M. Follstaedt, S.J. Hearne, T.A.Saif and I.M. Robertson, International Conference on Fracture, Greece 2006.  "Deformation and failure processes operating in ultra-fine grained materials.,"  European Conference on Fracture, Failure analysis of nano and engineering materials and structures, Greece 2006,  2006,  p. 744.

K. HattarJ. HanT.Saif I. M. Robertson.  "Development and Application of a MEMS-Based in-situ TEM straining device for Ultra-fine grained metallic systems,"  Microscopy and Microanalysis,  v.10,  2004,  p. 50.


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