Nanomechanics of Al/SiC Nanolayered CompositesDanny R.P. Singh & Nikhilesh Chawla, Arizona State University, DMR-0504781

100 nm Si

Al

SiC

Si=12 GPa

Hardness

Indenter hits Si

0

5

10

15

0 500 1000 1500 2000

Har

dne

ss (

GP

a)

Displacement (nm)

Al50SiC50

Al25SiC25

1 m

SiC fracture

Void growthIn Al

• 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

• Hardness determined by nanoindentation shows that increases in strength can be obtained by decrease the thickness of the Al and SiC layers

Focused Ion Beam Cross-section of Nanoindentation

As-processed Nanostructure

Nanomechanics of Al/SiC Nanolayered CompositesNikhilesh Chawla, Arizona State University, DMR 0504781

The Materials Research Society (MRS) has developed a traveling museum exhibit on Engineering Materials, termed Strange Matter.

The exhibit will come to Phoenix in the end of September 2007.

Prof. Chawla is assisting with hands-on activities for the general public, by making the facilities at ASU available to museum volunteers .

In one such activity a person will hammer nails in two conditions: as-received and annealed. This will show the difference in strength achieved by changes in microstructure through heat treatment. http://lucy.mrs.org/strangematter/

Mechanical Behavior of Metal/Ceramic Composite CoatingsYu-Lin Shen University of New Mexico DMR 0504781

Fig. 2. Modeling results showing possible failure pathes.

Fig. 1. Finite element modeling of elastic modulus derived from nanoindentation. Comparisons were made between the cases where the Al and SiC layers were explicitly accounted for and where the laminates were homogenized.

• One major objective of this research is to rationalize the experimental findings by numerical finite element modeling.

• Systematic finite element analyses have been conducted to examine the elastic modulus derived from the nanoindentation response, as well as to identify possible internal failure patterns.

• The indentation analysis spans a wide range from shallow depths (within the top layer) to deeper penetrations well into multiple layers. A homogenized multilayer model was also employed for the indentation modeling.

• A numerical modeling approach was developed for examining the buildup of residual stresses in the metallic layers caused by the peening effect during deposition. possible SiC fracture pattern

Mechanical Behavior of Metal/Ceramic Composite CoatingsYu-Lin Shen University of New Mexico DMR 0504781

Education Activities• A graduate student, Ms. Guanlin Tang, currently enrolled in

the doctoral program at UNM, has been performing the modeling work supervised by the Co-PI (Prof. Shen).

• To augment the current research on indentation behavior of layered composites, a high school student, Mr. Warren Chan (Randolph School, Huntsville, Alabama), worked in the Co-PI’s lab for eight weeks to conduct experiments and modeling of indentation of Al/SiC short fiber composites.

• An undergraduate student, Mr. Mohammed Haik, was hired and trained for developing the atomistic computer code for studying crystal defect interactions in metallic thin films. This was in preparation for the atomic-scale simulation studies on the multilayer system of this project.