Deformation behavior in Highly Nano-Twinned Cu

ChEMS Seminar

Dr. Andrea Hodge

Assistant Professor

Department of Aerospace and Mechanical Engineering

University of Southern California



Abstract:

The ductility and plastic flow behavior of highly aligned nanotwinned copper produced by interrupted magnetron sputtering is presented.  Tensile tests were performed at various strain rates at both room and liquid nitrogen temperatures.  Higher ductility and strength are reported for all samples tested at 77K.   The observed inhomogeneous deformation and shear band propagation are discussed as a function of the testing temperature, decreasing heat capacity at 77K and the low initial dislocation density which leads to a yield peak.  Uniformly distributed mobile dislocations introduced by rolling to 20% reduction in thickness eliminated the yield point at both temperatures.  The experimental observations clearly demonstrate that the observed yield-point behavior is a direct result of the very low initial dislocation density in these sputtered films as expected for ‘‘ideal” nanoscale microstructural materials.

Biography:

Dr. Andrea Hodge is the Philip and Cayley MacDonald Early Career Chair and assistant professor in the Aerospace and mechanical engineering department with a joint appointment in the Chemical and Materials Science Department.  Prior to her academia position she worked at Lawrence Livermore National Laboratory as a Staff Scientist from 2004 to 2007 and as a postdoctoral fellow from 2002-2004.  She received her Ph.D. in Materials Science from Northwestern University in December 2002.Professor Hodge leads the Materials Nanotechnology group at USC which includes a physical vapor deposition processing lab and a nanomechanics lab.  She received the TMS Young Leader Award in 2004, NSF CAREER award in 2010 and a Senior Fellow Alexander von Humboldt Fellowship in 2011.   Professor Hodge has co-authored over 50 peer-reviewed publications and a book chapter.