Effects of focused ion beam milling on the compressive behavior of directionally solidified micropillars and the nanoindentation response of an electropolished surface

Micropillar compression of LiF [111] single crystals: Effect of size, ion irradiation and misorientation

“…The FIB'ed pillars presented tapering angles of 2-3°, as expected from the annular milling process. These values are in agreement with the results published in the literature for micropiUars manufactured by FIB (Korte and Clegg, 2010;Zhang et al, 2006;Shim et al, 2009). …”

“…This way the truncation of dislocation sources originates the size effects Rao et al, 2008;Akarapu et al, 2010;Ngan, 2011). Recent studies in mechanically pre-strained Mo pillars, both with (Schneider et al, 2010) and without FIB milling (Shim et al, 2009), support this view, because size effects are independent of whether the initial defect distribution is due to FIB machining or mechanical pre-strain. This seems also to be the case for the [100] oriented LiF micropiUars, but not the for [111] oriented LiF pillars reported in this work.…”

Heterogeneous dislocation nucleation from surfaces and interfaces as governing plasticity mechanism in nanoscale metals

“…We highlight the variety of nanomechanical testing sample fabrication routes reported to date and their resulting initial microstructures, which have been found to have a significant impact on deformation behavior. [4][5][6][7][25][26][27][30][31][32][33][34][35][36][37] We compare our experimental results to the existing models that attempt to explain heterogeneous dislocation nucleation in pillar and thin film geometries. Further, we measure the experimental activation volumes as a means to test the applicability of these models to the deformation of our Cu nanopillars.…”

“…To investigate size effects in pillar geometries, several fabrication routes have been utilized: focused ion beam (FIB) fabrication, [4][5][6][7] vapor-liquid-solid growth, 26 directional solidification, [33][34][35] nanoimprinting, 36,37 cold welding, 27 and electroplating 25,[30][31][32] . FIBfabricated pillars have been studied most extensively, with average pillar diameters ranging from ;100 nm up to several microns.…”

“…[33][34][35] As grown, these square pillars contain zero initial dislocation densities and scanning electron microscopy micrographs appear to have pristine surfaces. As a result, these pillars have a sizeindependent strength under compression as they all attain nearly theoretical strengths at all sizes.…”