Center for Advanced Materials Research

Materials Research Science and Engineering Center

Welcome!

The MRSEC at Brown University began in 1996, and was renewed in 2000 And 2005. The current MRSEC research is focused on Micro- and Nano- Mechanics of Materials. The goals of the center are to 1) perform leading edge research in the mechanics of materials on multiple length scales down to the nano-scale and apply principles of solid mechanics to cell adhesion and other biological problems; 2) use the faculty and university resources to achieve broader impact in the areas of science education, technology transfer, human resource development and creation of a more diverse scientific community.

The goals of the center are to 1) perform leading edge research in the mechanics of materials on multiple length scales down to the nano-scale and apply principles of solid mechanics to cell adhesion and other biological problems; 2) use the faculty and university resources to achieve broader impact in the areas of science education, technology transfer, human resource development and creation of a more diverse scientific community. The MRSEC is administered through the Center for Advanced Materials Research (CAMR) at Brown University. The Director of the center is W.A. Curtin who is advised by an executive committee that contains a representative from each IRG (E. Chason, A. Bower) and the seed project (L.B. Freund).

Research in the current MRSEC is organized into the following topical areas: IRG1 - Stress in Thin Film and Small Scale Structures; IRG2 - Multiscale Mechanics of Complex Microstructures; seed project: Micromechanics of Cell Adhesion. Each project area consists of a strongly linked program of experimental and theoretical investigations. The synergy between theory and experiment, with new theoretical insights suggesting new experimental studies and new experimental results driving advances in modeling, is a hallmark of the center and in keeping with a strong tradition of collaboration at Brown. There is a high degree of interdisciplinarity in the program with multiple MRSEC members being involved in projects in more than one area.

Scientific Accomplishments: In the past year, MRSEC researchers published 43 scientific papers. Research highlights for the past year include:

Dramatic increases in computational speed have been achieved in front-tracking finite-element/cohesive-zone method models of the evolution of stress during the deposition of a thin polycrystalline film on a substrate, making possible parametric studies of the effect of material properties and processing conditions on the stress evolution, achieving excellent qualitative and quantitative agreement with experiments on both low and high mobility materials.
Computational methods coupling stress, surface kinetics and surface energetics have predicted the dynamical evolution of 7x7 domains on the technologically important Si(111) surface during deposition in agreement with experiments, showing the island shape changing from a concave shape to a branched morphology and demonstrating that the dependence of the step edge energy on orientation drives shaped bifurcations
Experimental study of the formation of Sn whiskers in coatings on Cu conductors has shown that plastic flow by dislocations plays in the Sn accommodates the volumetric expansion around the growing intermetallic particles but that an oxide layer prevents dislocations from escaping to relieve the stress. In contrast, alloy layers of Pb-Sn do not build up large stresses, attributed to absorption of dislocations in the grain boundaries of the Pb-Sn microstrucure.
A new model for dynamic strain aging in Al/Mg alloys has been created that predicts, from fundamental material properties, the strengthening versus strain rate in good agreement with experimental data (in collaboration with the GM/Brown CRL).
Experiments and computations of crack deflection at twist boundaries, using bi-crystals of Zn as a model system, have shown the toughening versus twist angle and the ability of a cystal-plasticity/cohesive-zone model to predict the propagation of cracks across the twist boundary.
The discrete dislocation method has been used to study size effects on plastic flow in polycrystalline metals, showing that the role of grain boundaries in blocking slip is key to the differences in the size dependence of single crystal and polycrystalline specimens, and the mechanisms for the size dependence have been elucidated.
A model accounting for thermal fluctuations of a membrane attached to a substrate at discrete points has been developed to understand the recent experimental discovery of a maximum spacing between molecular bonds for adhesion of a cell to a substrate.

Education and Outreach: Complementing the MRSEC research programs are dynamic and innovative outreach programs in the area of education and technology. Our program to train and send Brown undergraduates to visit local middle schools has reached over 3900 students as well as influencing the undergrads performing the visits. A number of Brown students who participated in the program have gone on to careers in science education. Our RET program provides local educators with a summer experience to develop new curricular materials in collaboration with our faculty. The summer REU program attracts excellent students from a range of national universities including students from under-represented minorities. This program is enhanced through collaboration with the Leadership Alliance to recruit students and encourage them to pursue careers in science. Outreach activities are coordinated with partners at other institutions (primarily Florida A&M University) to increase participation from a diverse pool of students. Collaborative activities with industrial partners remain a strong component of the center. A centerpiece of this effort is the Collaborative Research Lab with General Motors that was renewed last year. Additional industrial interactions with Caterpillar, EMC Corp. and others maintain a strong link between the Center’s research and technological applications.

Broader Impacts: The broader impact of the Center‘s activities are both scientific and educational. The results of our research affect the scientific community through the dissemination of our results, development of new experimental techniques for observing nanoscale and biological phenomena, and development of theoretical methods that advance our analytical capabilities and fundamental understanding. Through the interactions with our industrial partners, these advances are applied to issues of technological importance, such as the development of stronger materials or the processing of electronics without the use of environmentally hazardous materials. The educational activities of the Center impact the entire Rhode Island community, bringing our faculty and students in contact with students and teachers in the local schools. Our summer programs bring in students from a wider area, with emphasis on recruitment and retention of groups that are under-represented in the sciences and engineering. Finally, the training of graduate students is instrumental in creating the next generation of leaders in the areas of solid mechanics and materials science.

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