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 0748267DMR 0748267

Figure 1. (a) Fabrication steps: E-beam lithography/electroplating. (b) TEM image of nano-twinned Cu pillar w periodic <111> twin boundaries (diffraction pattern in inset) (c ) ion image of Cu nano-pillar with some twin boundaries (d) 100nm single crystalline Cu nano-pillar for tensile testing (e) pillar array for testing (circles etched as markers post-fabrication)

1. E-beam patterning 2. Electroplating

3. Pillars in PMMA matrix4. Free-standing pillar array

20 nm

(a)(b)

(c)(d) (e)

Key Accomplishments:1. Developed FIB-less nano-pillar fabrication methodology2. Uniaxial compression and tension experiments reveal:-Smaller is Stronger for fcc and bcc metals-Smaller is Weaker for nanocrystalline metals-Smaller is Stronger and more Ductile for metallic glasses-Tension-compression asymmetry and strain rate sensitivity in bcc nano-pillars-Cu nano-pillars are strain rate sensitive below 150nm implying surface dislocation nucleation

UNDERGRADUATE STUDENTSUNDERGRADUATE STUDENTSTroy Sandberg (Caltech SURF)Cameron Gross (Caltech SURF)

Sun Lin (Natl U of Signapour)Yeojun Chun (Caltech SURF)Warren Cai (Caltech SURF)

Ana Fernandez (SURF)POST-DOCSPOST-DOCSJu-Young Kim (Ph.D. SNU)

Mingyuan Huang (Ph.D. Columbia U.)Dongchan Jang (PhD. U Mich.)

GRADUATE STUDENTSGRADUATE STUDENTSShelby Hutchens (5th year)Andrew Jennings (3rd year)

Allison Kunz* (2nd year)Clara Cho (2nd year)

Joanna Kolodziejska (1st year)Zach Aitken (1st year)

RELEVANT PUBLICATIONS (2009-2010):-Kaul, K.G. et al Nanotechnology 21, 315501 (2010).-A.T. Jennings, et al Phys Rev Lett, 104, 135503 (2010).-D. Jang, J.R. Greer Nature Materials, 9, 215-219 (2010).-G. Lee, et al, Acta Materialia, 58 (4) 1361-1368 (2010).-J.-Y. Kim, et al, Acta Materialia 58 (2010) 2355-2363. -M. J. Burek, J. R. Greer Nano Letters, 10, 69-76 (2009).-J.R. Greer, et al, J of Materials 61 (12) 19-25 (2009). -J.R. Greer, et al Adv. Func. Materials 19, 2880-6 (2009)

HIGH SCHOOL STUDENTSHIGH SCHOOL STUDENTSNancy Fann, Jaya Chandra

BROAD IMPACT PI is faculty advisor for Society of Women Engineers (SWE) and Women Mentoring Women

SEMINARS (2009-2010):UC Berkeley, Yale, Sandia NL, UC Riverside, Trinity College (Ireland) (2010), USC, Johns Hopkins U, USC ,MIT, U Michigan, Notre Dame

CONFERENCES (2009-10): MRS, TMS, GRC, ASME, ECI, EIPBN (3-beam), Plasticity 2010, 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 0748267DMR 0748267