3.
032 Mechanical Behavior of Materials
Fall 2007
shear bands (red) forming in
polycrystalline elemental metal
with many line and point defects
Images removed due to copyright restrictions.
Please see:
http://www-geol.unine.ch/03_france/granites/Granites-Thumbnails/3.jpg
shear bands in granite
(complex crystal) formed
under pressure and
temperature
Image sources: N. Ghoneim (UCLA), osiris.seas.ucla.edu/bottom.html;
http://www-geol.unine.ch/03_france/granites/Granites-Thumbnails/3.jpg Lecture 20 (10.26.07)
3.032 Mechanical Behavior of Materials
Fall 2007
Images removed due to copyright restrictions. bulk amorphous metals
Please see: (aka, bulk metallic glasses or
http://www.ornl.gov/info/ornlreview/v38_1_05/images/a17_golf_full.jpg amorphous alloys)
http://www.csem.caltech.edu/graphics/shear-bands.jpg
• Yielding via shear banding
Fig. 3 and 4 in Mukai, Toshiji, et al. “Dynamic response of a Pd40Ni40P20 bulk • Yield stress depends on
metallic glass in tension.” Scripta Materialia 46 (January 2002): 43-47.
compression vs. tension
shear bands
Ni-Nb-Sn amorphous metals:
E ~ 200 GPa (steel)
σy(compression) ~ 3 GPa (3x steel)
σy (tension) ~ 1 GPa (steel)
Strain at failure ~ 1% (glass)
Image sources: Lu and Liu (Oak Ridge National Lab). www.ornl.gov/v38_1_05/article17.shtml
E. Pekarskaya and W. Johnson (CalTech). www.csem.caltech.edu/Facilities/tem.html
Data sources: Applied Physics Letters, 82: 1030–1032, (2003); TG Nieh, Bulk Metallic Glasses, Ch. 6. Lecture 20 (10.26.07)
3.032 Mechanical Behavior of Materials
Fall 2007
fibrils of polymer
hydrocarbon chains
aligned within fibril
crazing in amorphous polymer
rupture of fibrils under
tensile load
Image sources: http://www.kern-gmbh.de/index_glossar.html?http://www.kern-gmbh.de/kunststoff/service/glossar/crazing.htm;
Lecture 20 (10.26.07)
