[Stanford Nano Society Seminar] Tomorrow 12pm - 1pm, McCullough 115, Mechanical Properties of Small Scale Materials Using Nanoindentation
gthareja at stanford.edu
Thu May 7 22:33:30 PDT 2009
Stanford Nanoscience & Nanotechnology Society Seminar:
Mechanical Properties of Small Scale Materials Using Nanoindentation
Speaker - Dr. Seung Min Han
Bio - Dr. Han graduated with Ph.D. from Dr. William Nix’s group in Materials Science and Engineering in 2006, and joined the MSE department as an Acting Assistant Professor since then. Dr. Han is currently also part of Dr. Yi Cui’s group for in-situ TEM nanoindentation of nanosturctures.
Location: McCullough 115
Time: 12:00 noon - 1:00pm
Date: May 08(Friday) – Tomorrow!
As the dimensions of today’s devices become smaller and smaller, understanding the mechanical properties of materials at sub-micron length scales becomes more challenging. The conventional methods for evaluating strengths of materials in bulk form cannot be applied, and new methodologies are required for accurately evaluating mechanical properties of thin films. In this study, the method of microcompression testing, which involves using a focused ion beam to synthesize sub-micron sized pillars and subsequently testing with a flat punch tip of a nanoindenter, is used to evaluate mechanical properties of Al-Al3Sc multilayers with varying bilayer thicknesses from 6-100nm. The measured yield strengths show the trend of increasing strength with decreasing bilayer period, and agree with the nanoindentation hardness results upon applying the suitable Tabor factor correction. The deformation of the Al-Al3Sc pillars at large strains showed strain softening that causes inhomogeneous deformation. A new model was developed to account for the inhomogeneous geometry to calculate the stress-strain in this regime of strain softening. A TEM study of deformed pillar showed shearing and rotation of layering structure that could be responsible for the observed strain softening behavior.
For more information please visit http://nanosociety.stanford.edu
Pizzas would be served!
All are welcome !
Ph.D candidate, Nishi group
420 Via Palou Mall, CISX 128
Stanford, CA 94305
Email: gthareja at stanford.edu
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