MSE Pritchett Lecture - Enrique J. Lavernia, Distinguished Professor
NANOSTRUCTURED METALS AND COMPOSITES: FROM THE NANOSCALE TO THE MICROSCALE
Enrique J. Lavernia, Distinguished Professor
Department of Chemical Engineering and Materials Science
University of California, One Shields Ave., Davis, CA 95616, USA
Bulk nanostructured materials and composites have matured into a new class of materials that is being considered in a variety of engineering applications. The successful synthesis of large-scale nanostructured materials is of technological and scientific significance. From a technological point of view, it will be feasible to obtain engineering materials that retain the structural and chemical attributes of particles/grains in the nanometer size range. From scientific point of view, large-scale nanostructured materials will permit systematic investigations of the physical and mechanical behavior, as well as novel phenomena.
Recently, severe plastic deformation (SPD), which encompasses mechanical alloying in liquid nitrogen (cryomilling) and high-pressure torsion, has emerged as a successful strategy for the synthesis of nanostructured alloys and composites. Results from various groups around the world reveal considerable improvements in the physical performance of a variety of SPD processed metals and alloys. While increases in strength of several 100% are commonly documented, ductility, however, appears to scale inversely with strength in these materials; this behavior has been attributed to limited dislocation activity at these length scales. This challenge has been addressed via the introduction of additional size scales that facilitate plasticity during deformation. The concept of a bimodal microstructure has recently been extended into the realm of metal composites with tri-modal microstructural characteristics, to accomplish ultra-high strength values. In this lecture, published data of cryomilled alloys and composites are reviewed and discussed with particular emphasis on the following topics: recent findings in the area of cryomilled materials; primary consolidation and secondary processing methods; microstructural evolution from nanostructured powders to bulk materials during consolidation; and mechanical behavior of consolidated materials. The deformation behavior and the underlying mechanisms of cryomilled materials are discussed in an effort to shed light into the fundamental behavior of ultrafine grained and nanostructured materials.
Enrique J. Lavernia returned as dean to the College of Engineering on January 1, 2011 after serving as provost and executive vice chancellor of the University of California, Davis, from January 2009–December 2010. He joined the campus in 2002 as dean of the College of Engineering, where he was also promoted to Distinguished Professor in 2007. Prior to his arrival to Davis in 2002, Lavernia served as Chair and Chancellor’s Professor in the Department of Chemical Engineering and Materials Science at UC Irvine. He was named the 1998 Biochemical and Biochemical Engineering Materials Science “Science Teacher of the Year” at UCI. Elected to the National Academy of Engineering in 2013, Lavernia is also a fellow of the American Association for the Advancement of Science (2000); a fellow of the American Society of Mechanical Engineers (2006); and fellow of ASM International (1998).
Dean Lavernia is a Fellow of the American Association for the Advancement of Science, the American Society of Mechanical Engineers, the ASM International, and the Alexander von Humboldt Foundation. Named Presidential Young Investigator by the National Science Foundation, Lavernia also received a Young Investigator Award from the Office of Naval Research. In 2011 he received the Hispanic Engineer National Achievement Award (HEENAC) and the Society for the Advancement of Chicanos and Native Americans in Science (SACNAS) Distinguished Scientist Award. Dean Lavernia is also the recipient of the 2013 Edward DeMille Campbell Memorial Lectureship, and the 2013 ASM International Gold Medal Award.
Dean Lavernia’s research interests include synthesis of structural materials and metal matrix composites with particular emphasis on processing fundamentals; thermal spray processing of nano-structured materials; spray atomization and deposition of structural materials; solidification processing of metal matrix composites; synthesis and behavior of nano-crystalline materials; and mathematical modeling of advanced materials and processes. He has published 400 journal and 200 conference publications on topics ranging from nano-materials to aluminum alloys.
Dean Lavernia earned his B.S. with Honors in Solid Mechanics from Brown University in 1982, his M.S. in Metallurgy from the Massachusetts Institute of Technology (M.I.T.) in 1984, and his Ph.D. in Materials Engineering from M.I.T. in 1986.