Key Accomplishments:
2
Motivation: Mechanical properties of materials are different when sample dimensions are reduced to nano-scale. Conducting in-situ experiments at that scale is challenging yet necessary to understand true deformation mechanisms and to develop new materials. CAREER: Experimental Investigation of Plasticity at CAREER: Experimental Investigation of Plasticity at Nano-scale Nano-scale Julia R. Greer, California Institute of Technology, DMR 0748267 Key Accomplishments: 1.ALD-assivated Cu nano-pillars: exhibit significant hardening, Bauschinger effect; stochastic behavior remains (A. Jennings, S.-W. Lee, Z. Aitken) 1 2.Intermittent Plasticity of Single Crystalline Nano-Pillars: Scaling-collapse and scaling-function extracted from compression experiments show that nano- plasticity reflects tuned criticality as opposed to self-organized criticality (SOC). Power-law exponents and scaling- function agree with mean-field theory (MFT) predictions (A. Jennings) 3.Nanocrystalline Pt: Developed a FIB-less nano-fabrication methodology to create 12nm-grained nc-Pt nano-pillars. Compressive strengths were found to not deviate significantly from bulk even at smallest pillar diameters, ~8 grains across. Sample size independent regime was identified and shown to depend on both
description
CAREER: Experimental Investigation of Plasticity at Nano-scale Julia R. Greer, California Institute of Technology, DMR 0748267. - PowerPoint PPT Presentation
Transcript of Key Accomplishments:
Motivation: Mechanical properties of materials are different when sample dimensions are reduced to nano-scale. Conducting in-situ experiments at that scale is challenging yetnecessary to understand true deformation mechanisms and to develop new materials.
CAREER: Experimental Investigation of Plasticity at Nano-scale CAREER: Experimental Investigation of Plasticity at Nano-scale Julia R. Greer, California Institute of Technology, DMR 0748267
Key Accomplishments:1.ALD-assivated Cu nano-pillars: exhibit significant hardening, Bauschinger effect; stochastic behavior remains (A. Jennings, S.-W. Lee, Z. Aitken)1
2.Intermittent Plasticity of Single Crystalline Nano-Pillars: Scaling-collapse and scaling-function extracted from compression experiments show that nano-plasticity reflects tuned criticality as opposed to self-organized criticality (SOC). Power-law exponents and scaling-function agree with mean-field theory (MFT) predictions (A. Jennings)3.Nanocrystalline Pt: Developed a FIB-less nano-fabrication methodology to create 12nm-grained nc-Pt nano-pillars. Compressive strengths were found to not deviate significantly from bulk even at smallest pillar diameters, ~8 grains across. Sample size independent regime was identified and shown to depend on both grain size and the ratio of external sample size to grain size. (X. W. Gu)
NSF-SUPPORTEDNSF-SUPPORTEDUNDERGRADUATE STUDENTSUNDERGRADUATE STUDENTSColleen Loynachan (MIT SURF)
Jacqueline Masehi-Lano (Caltech SURF)Matt Wraith (UIUC SURF)
NSF-SUPPORTED NSF-SUPPORTED GRADUATE STUDENTSGRADUATE STUDENTS
Z. Aitken (2nf year)X. Wendy Gu (partial)
L. Meza (partial)
RELEVANT PUBLICATIONS (2011-2012):-A. T. Jennings, et al “Higher Compressive Strengths and Bauschinger Effect in Conformally-Passivated Copper Nanopillars” Acta Mater. 60 (8), (2012)-N. Friedman, et al “Statistics of dislocation slip-avalanches in nano-sized single crystals show tuned critical behavior predicted by a simple mean field model.” Phys Rev Lett (in press, 2012) -A. Jerusalem, et al “Continuum modeling of dislocation starvation and subsequent nucleation in nano-pillar compression.” Scripta Mater. 66 (2), (2012)-C.R. Weinberger, et al “Atomistic simulations and continuum modeling of dislocation nucleation and strength in gold nanowires” J Mech Phys Solids 60, 84-103 (2012)
HIGH SCHOOL STUDENTSHIGH SCHOOL STUDENTSBill Guo (Arcadia HS)
Madeline Watkins (Mayfield HS) Annie Wu (Los Osos HS)
BROAD IMPACT PI is faculty advisor for Society of Women Engineers (SWE) and Women
Mentoring Women (WMW)
SEMINARS (2011-2012):Harvard, U Tennessee, Ecole Polytechnique, RPI, U Tennessee, IMDEA, UIUC, Northwestern
CONFERENCES (2011-12): MRS, TMS, ASME, ECI, Plasticity 2012, SES, Gordon, NANO2012, MMM, ISMEN, and
Several“Micromechanics” and “Nano-materials” workshops
CAREER: Experimental Investigation of Plasticity at Nano-scale CAREER: Experimental Investigation of Plasticity at Nano-scale Julia R. Greer, California Institute of Technology, DMR 0748267
