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Timothy P. Weihs Professor of Materials Science and Engineering Ph.D. Materials Science and Engineering, Stanford University, 1990 M.E. Materials Science and Engineering, Thayer School of Engineering, 1985 B.E. Engineering, Thayer School of Engineering, 1985 B.A. Engineering Sciences, Dartmouth College, 1983 |
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The work on nanostructured materials investigates self-propagating reactions, solid state transformations, and mechanical deformation in films and foils with nanoscale layering. Samples are fabricated using a large, planetary magnetron sputtering system, and they are characterized using TEM, XRD, calorimetry, and mechanical techniques at room and elevated temperatures. Commercial applications include rapid heat sources, bonding, and protective coatings. Several of these applications are being pursued in collaboration with industrial partners. In addition to nanoscale multilayer foils, Professor Weihs and his group also fabricate and characterize microlaminate foils. They measure interface energies in these samples using unique zero creep techniques and they quantify the stability and the strength of the layered structures for high temperature applications. Facilities include high temperature furnaces for both uniaxial tension tests and biaxial wafer curvature measurements. The research on thin film metallizations explores the stability of materials that are used as interconnects on modern integrated circuits. Al alloys, elemental Cu, and barrier layer materials are of most interest. The thermal stresses, growth stresses, grain growth, and texture effects inherent in these materials are investigated using homogeneous films and patterned lines. This research is performed in conjunction with major IC manufacturers. The last area of research covers the growing field of micromechanical and nanomechanical characterizations. Professor Weihs and his group are developing new methods for measuring mechanical properties of very small volumes of material, and they are applying these techniques to novel material systems. For example, bone and teeth are fascinating composites with individual components that measure a micron or less in at least one dimension. The mechanical properties of these individual components are quantified using point probe techniques. Other material systems that are examined include electrochemically controlled surfaces and structural composites. |
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Selected Publications
Weihs, T. P. "Self-Propagating Reactions in Multilayer Materials." Invited chapter in Handbook of Thin Film Process Technology, IOP Publishing, Accepted June, 1997. (Invited Review)
Mann, A., A. Gavens, M. Reiss, D. van Heerden, G. Bao, and T.P. Weihs. "Predicting the Characteristics of Self-Propagating Exothermic Reactions in Multilayer Foils." J Appl Phys 82(1997): 1178. Weihs, T. P., M.A. Wall and T.W. Barbee, Jr. "A Low Temperature Technique for Measuring Enthalpies of Formation." J Mater Res 11(1996): 1403. |
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Michalelsen, C., K. Barmak, and T.P. Weihs. "Investigating the Thermodynamics and Kinetics of Thin Film Reactions by Differential Scanning Calorimetry." J Phys D: Appl Phys Dec. 1997. (Invited Review) Weihs, T. P. and T.W. Barbee, Jr. "Hardness, Ductility, and Thermal Processing of Cu/Zr and Cu/Cu-Zr Nanoscale Multilayer Foils." Acta Mater 45(1997): 2307. Kinney, J. H., M. Balooch, S.J. Marshall, G.W. Marshall,Jr., and T.P. Weihs. "Hardness and Young's Modulus of Peritubular and Intertubular Dentine: Dependence of Mechanical Properties on Intra-tooth Position." Archives of Oral Bio 41(1996): 9 Weihs, T. P., Z. Nowaz, S.P. Jarvis and J.B.Pethica. "Limits of Imaging Resolution for Atomic Force Microscopy of Molecules." Appl Phys Lett 29(1991): 3536. Selected Patents Barbee, Jr., T. W. and T.P. Weihs. "Self-Propagating Exothermic Reactions in Multilayer Materials." U.S. Patent 5,538,795, July 23, 1996. |
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