Radial Inner Morphology Effects on the Mechanical Properties of Amorphous Composite Cobalt Boride Nanoparticles

Antonio Rinaldi, Silvia Licoccia, Enrico Traversa, Karl Sieradzki, Pedro Peralta, Ana B. Dávila-Ibáñez, Miguel A. Correa-Duarte, and Veronica Salgueirino

J. Phys. Chem. C, 2010, 114, 13451–13458

The manuscript reports on quantitative microcompression tests performed on novel composite nanoparticles (CNPs) consisting of cobalt boride coated with silica. This material exhibits a complex three-regimes response that entails both elastic and plastic deformation, and may result from several concurring deformation processes (i.e., mechanical, chemical, and magnetic). The results are interpreted in consideration of the pre-existent distribution of radial defects found in the cobalt boride core of the CNPs. Such defects represent a signature feature of such nanocomposites, which sets them apart from any defect-free, single-phase nanoparticle reported previously, and are of great relevance to both reverse plasticity and strain hardening (i.e., proper irreversible plasticity) effects observed. Since the mechanical response is actively pursued for MEMS and NEMS applications (central to these efforts is addressing the relationship between confined volumes and applied stress), the reported results become a major step toward the full potential of nanostructures and consequently of the next generation device technologies.