Digital Repository, ICF12, Ottawa 2009

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Size and Stress State Effects on Plasticity Mediated Brittle Fracture
W.W. Gerberich, A.R. Beaber, D.D. Stauffer

Last modified: 2013-05-07


Brittle to ductile transitions (BDTs) in ceramics might seem like trivial pursuitexcept for high temperature applications. However, the emergence ofnanotechnology devices has changed the horizon. For example, to lower theBDT, one can decrease the component size. This is not the same sizephenomenon that has traditionally been associated with Weibull statistics. It isproposed here with experimental evidence and a physically based theoreticalmodel that there are potentially large shifts in BDTs of some device materialsbased on size and stress state. This would be applicable to manysemiconductors, oxides, carbides and nitrides. Both dislocation nucleation(strength) and discretized shielding (fracture) are invoked, partially based onobservations in Si, SiC and MgO as provided by nanowire, nanosphere and smallvolume nanoindentation evaluations. It is proposed that activation volumes fordeformation and fracture of silicon nanospheres are the key physical quantity inthe scaling of the BDT.

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