Modeling the Size-Dependent Strength of Metallic Nanoparticles at the Nanoscale
Dan Mordehai (Technion), Seok-Woo Lee (CalTech), David Srolovitz (University of Pennsylvania), William Nix (Stanford University), Eugen Rabkin ()
From Atomistics to Reality: Spanning Scales in Simulations and Experiments Symposium A
Tue 10:45 - 12:15
CIT 165
It is well accepted that the strength of single crystalline metallic specimens depends strongly on their characteristic microstructural length scale at the sub-micrometer scale. In this talk, a combined experimental/computational study of the mechanical properties of nanoparticles will be presented. Faceted nanoparticles with various lateral dimensions were created via the agglomeration of a polycrystalline film on a sapphire surface. The nanoparticles were deformed under compression. Most of the nanoparticles yielded at compression stresses in the GPa regime with a huge strain burst. Moreover, the compressive stress at the onset of plastic deformation depends strongly on the nanoparticle diameter. Molecular Dynamics (MD) and Finite Elements Modeling (FEM) are employed separately to understand the size effect observed. The particles strength for compression in the atomistic simulations exhibited a strong size effect, which can be described by a power-law. Based upon the FEM of the stresses which develop within the nanoparticles during compression, a size-dependent dislocation nucleation model is suggested. The model rationalizes the observed size dependency under compression.