Harsh Deep Chopra
DMR Division of Materials Research
MPS Directorate for Mathematical & Physical Sciences
Start Date:
August 1, 2002
Expires:
July 31, 2007 (Estimated)
Awarded Amount to Date:
$1230333
Investigator(s):
Kevin Hemker hemker@jhu.edu (Principal Investigator)
En (Evan) Ma (Co-Principal Investigator) Jean-Francois Molinari (Co-Principal Investigator)
Sponsor:
Johns Hopkins University
3400 N CHARLES ST
BALTIMORE, MD 21218 410/516-8668
NSF Program(s):
WESTERN EUROPE PROGRAM, METAL & METALLIC NANOSTRUCTURE, DMR SHORT TERM SUPPORT, NANOSCALE: INTRDISCPL RESRCH T, MATERIALS AND SURFACE ENG
Field Application(s):
0106000 Materials Research
Program Reference Code(s):
AMPP, 9162, 5918, 1674, 1589
Program Element Code(s):
5980, 1771, 1712, 1674, 1633
ABSTRACT
This project is a collaborative inter-disciplinary research to elucidate and model the deformation and fracture mechanisms of nanostructured materials. These studies are important for the reliability of next-generation MEMS, NEMS, magnetic and ultra-hard films, and micro/nano devices, in general, that are closely tied to their mechanical performance. A major objective is to obtain a thorough and solid understanding of operative deformation mechanisms operative in nanoscale materials. The study is specifically designed to probe the mechanical response of materials at nano-scales. Novel designs for in situ TEM observations and microsample tensile and transient experiments will be used to uncover and characterize the dominant deformation and fracture mechanisms in high purity vapor and electro-deposited nanostructured thin films. Multi-scale finite element calculations containing physical models will be developed based on the experimental findings. These models along with adaptive meshing and cohesive elements with atomistic descriptions of grain boundaries in nanocrystalline materials will be used to develop models to predict the collective macroscopic response of a compilation of nanocrystalline grains. The undergraduate and graduate students and post-doctoral fellows engaged in this project would be co- advised. Two parallel teams, each including a post-doc, graduate student and an undergraduate research assistant, will be formed and mentoring skills will be developed at all levels.
The overriding intellectual challenge of the proposed study is to develop a science based methodology for measuring, describing and modeling deformation and fracture processes at or near nanometer length scales. The results will have application in MEMS, NEMS and other technologies where magnetic and ultra-hard films are used. This project brings together a synergistic combination of expertise on the synthesis of nanocrystalline materials, the electron microscopy, microsample testing, and adaptive meshing and cohesive element modeling. The importance of teamwork is emphasized and all participants will be educated to work in an inter-disciplinary multi-scale environment at the nano scale.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
D.H. Warner and J.F. Molinari. "Atomistic-Based Continuum Modeling of Nanocrystalline Copper," TMS Letters, v.7, 2004, p. 147.
D.S. Gianola, K.J. Hemker, M. Legros, and W.N. Sharpe, Jr. "Experimental techniques for uncovering deformation mechanisms in nanocrystalline Al thin films," TMS Letters, v.1, 2004, p. 7.
Gianola, DS; Sharpe, W. "Techniques for testing thin films in tension," EXPERIMENTAL TECHNIQUES, v.28, 2004, p. 23-27.
Gianola, DS; Van Petegem, S; Legros, M; Brandstetter, S; Van Swygenhoven, H; Hemker, KJ. "Stress-assisted discontinuous grain growth and its effect on the deformation behavior of nanocrystalline aluminum thin films," ACTA MATERIALIA, v.54, 2006, p. 2253-2263.
Gianola, DS; Warner, DH; Molinari, JF; Hemker, KJ. "Increased strain rate sensitivity due to stress-coupled grain growth in nanocrystalline Al," SCRIPTA MATERIALIA, v.55, 2006, p. 649-652.
Hemker, KJ. "Understanding how nanocrystalline metals deform," SCIENCE, v.304, 2004, p. 221-+.
Hemker, KJ; Sharpe, WN. "Microscale characterization of mechanical properties," ANNUAL REVIEW OF MATERIALS RESEARCH, v.37, 2007, p. 93-126.
Mingwei Chen, En Ma, K.J. Hemker. "Mechanical Behavior of Nanocrystalline Metals," Chapter 17 in the Handbook of Nanomaterials, 2006, p. 497.
Sansoz, F; Molinari, JF. "Incidence of atom shuffling on the shear and decohesion behavior of a symmetric tilt grain boundary in copper," SCRIPTA MATERIALIA, v.50, 2004, p. 1283-1288.
Sansoz, F; Molinari, JF. "Mechanical behavior of Sigma tilt grain boundaries in nanoscale Cu and Al: A quasicontinuum study," ACTA MATERIALIA, v.53, 2005, p. 1931-1944.
Wang, YM; Wang, K; Pan, D; Lu, K; Hemker, KJ; Ma, E. "Microsample tensile testing of nanocrystalline copper," SCRIPTA MATERIALIA, v.48, 2003, p. 1581-1586.
Warner, DH; Sansoz, F; Molinari, JF. "Atomistic based continuum investigation of plastic deformation in nanocrystalline copper," INTERNATIONAL JOURNAL OF PLASTICITY, v.22, 2006, p. 754-774.
