NEES Teleseminars

Event Information

EFRC NEES Teleseminar: Raman Spectroscopy to Measure Stress of Eutectic Si Particles in Cast Al
Tuesday, November 17, 2015
4:00 p.m.-5:30 p.m.
A.V. Williams Building, Room 2168
For More Information:
Martha Heil
301 405 0876
mjheil@umd.edu

Steve Harris, Lawrence Berkeley National Laboratory

November 17, 2015

4:00 – 5:30pm

A.V. Williams Building, Room 2168

 

Abstract: While micro-Raman spectroscopy has been used in the past to measure local stresses in Si and other cubic materials, the analyses were almost always limited to cases with simple (i.e., scalar) stress states, such as uniaxial or equibiaxial stress. We have provided an experimental methodology to determine the full (tensor) state of stress in Si wafers of different orientations, which we then extended to interrogate stress states in Si particles embedded in an cast Al-Si alloy. Such measurements are important for predicting ductility of cast Al alloys, since a primary source of damage is cracking of eutectic Si particles. Stress states were determined both in the as-received residually stressed state and under in situ uniaxial loading. Comparison with finite element calculations shows good agreement.


Bio: Harris received a BA in Chemistry from UCLA in 1971 and a PhD from Harvard in Physical Chemistry in 1975. After a Miller Fellowship at Berkeley, he moved to the General Motors Research Lab, where he eventually became a Technical Fellow. Apart from a 9-year stint at the Ford Scientific Research Labs, Harris worked at GM until 2012, when he was awarded a Miller Visiting Professorship in the Berkeley Chemistry Department. Since then he has worked in the Materials Science Division at Lawrence Berkeley Lab. Harris’ work has ranged widely, including combustion chemistry, development of CVD films, aerosol dynamics modeling, chemo-mechanical polishing, and fracture mechanics. When he returned to GM in 2007 he started work on Li-ion batteries, focusing on demonstrating the existence of heterogeneities in batteries and their effects on ion transport, durability, and energy density.

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