Size-Dependent Strength in Single-Crystalline Metallic Nanostructures

摘要: The emergence of a substantial body literature focusing on uniaxial compression experiments micro- and nano-sized single-crystalline cylindrical papers has unambiguously demonstrated that, at these scales, the sample dimensions dramatically affect crystalline strength (for reviews, see [1-3]). In most experimental studies, pillars with diameters ranging from ~ 100 nm up to several micrometers were fabricated, largely by use focused ion beam (FIB) method, some non-FIB-based methods as well, subsequently compressed in nanoindenter custom-made flat punch indenter tip. More recently, small-scale mechanical behavior also been explored through tensile experiments, usually performed inside in-situ scanning electron microscopes (SEM)- or transmission (TEM)-with custom-built deformation instruments small number research groups [3-6]. Intriguingly, results all reports for metals variety crystal structures - face-centered cubic (fcc), body-centered (bcc), hexagonal close-packed (hcp), tetragonal -show power-law dependence between flow stress pillar diameter. Further, within fcc family, slopes tested converge unique value approximately -0.6 [1-3,7] (see Figure 7.1), which is not case other crystals.