Multilayered materials are ubiquitous in nature and in engineered structures

1. Nanomechanics of Al/SiC Nanolayered CompositesNikhilesh Chawla, Arizona State University, DMR 0504781 • Multilayered materials are ubiquitous in nature and in engineered structures • Our research focuses on novel metal-ceramic multilayers with a combination of high strength and toughness • Transmission electron microscopy was used to understand deformation behavior under nanoindentation • A novel deformation mechanism was identified, whereby the Al grains are “flattened” (circled in red in the figure) and extruded between the hard SiC layers (as shown the Al grain aspect ratio measurements in the table). indentation Al SiC 100 nm Al Grain Aspect Ratio Collaborators: P.-L. Sun, Feng Chia University, Taiwan T.-Y. Lin and J.P. Chu, National Taiwan University of Science and Technology, Taiwan

2. Nanomechanics of Al/SiC Nanolayered CompositesNikhilesh Chawla, Arizona State University, DMR 0504781 • Broader Impacts • Prof. Chawla was invited to participate and be interviewed in the popular show “Modern Marvels” which is broadcast by the History Channel • The show is called “Breaking Point” and focuses on the strength, fracture, and testing techniques of various types of every-day materials • Among other things, Prof. Chawla’s research activities are showcased including his NSF-DMR sponsored research • The program is slated to air in 2009. High speed image of human hair tested in tension

3. Mechanical Behavior of Metal/Ceramic Composite CoatingsYu-Lin ShenUniversity of New Mexico DMR 0504781 Nikhilesh Chawla, Arizona State University, DMR 0504781 • One major objective of this research is to rationalize the experimental findings by numerical finite element modeling. A recent focus is on the compression of Al/SiC multilayered micropillars. • A strong dependence of the pillar compression response on the specimen geometry was found. • It is essential to correct the raw data by taking into account the compliance of the pillar base and the machine. • A tapered side wall was found to affect the modulus and stress-strain response only slightly. Taper, however, can affect the overall deformation configuration dramatically. In the tapered Al/SiC multilayer pillar, the Al layers in the upper portion tend to deform much more severely and protrude sideways. indenter Fig. 1. Deformation configuration in the Al/SiC micropillar during compression.

4. Mechanical Behavior of Metal/Ceramic Composite CoatingsYu-Lin ShenUniversity of New Mexico DMR 0504781 Nikhilesh Chawla, Arizona State University, DMR 0504781 Education Activities • A graduate student, Ms. Guanlin Tang, was performing the modeling work supervised by the Co-PI (Prof. Shen). She received her Ph.D. in August 2009. • An undergraduate student, Mr. Mohammed Haik, was trained by the Co-PI to develop computer codes for studying crystal defect interactions in metallic thin films. • An M.S. student, Ms. Kiranmaye Aluru, has been undergoing training in the Co-PI’s group for conducting numerical modeling of deformation and failure in composite structures.