The mechanical strengths of Au and Mo single-crystal pillars of sub-micrometer diameter in uniaxial compression tests were compared. Both crystals exhibited an increase in flow stress with decreasing diameter, but the change was more pronounced in Au than in Mo. The ratio between the observed maximum flow stress and the theoretical strength was much larger in Au pillars than in Mo pillars. Dislocation dynamics simulations also revealed different dislocation behavior in these two metals. While in a face-centred cubic crystal a dislocation loop nucleated from the surface simply moves on its glide plane and exits the pillar, in a body-centred cubic crystal it could generate multiple new dislocations due to the ease of screw dislocations to change slip planes. It was postulated that this difference in dislocation behavior was the fundamental reason for the observed difference in the plastic deformation behaviors of face-centred cubic and body-centred cubic pillars.

Comparing the Strength of FCC and BCC Sub-Micrometer Pillars - Compression Experiments and Dislocation Dynamics Simulations. J.R.Greer, C.R.Weinberger, W.Cai: Materials Science and Engineering A, 2008, 493[1-2], 21-25