Abstract Scope |
BNNT is a fibrous nanomaterial with excellent strength and stiffness, which can be exploited to augment the mechanical properties of low-density metals like Al, Mg and Ti. The composites display a hierarchical microstructure, composed of a metal-matrix with dispersed ceramic nanotubes and interfacial products formed due to chemical reactions between the metal and BNNT during high-temperature processing. In-situ mechanical investigations are performed in high-resolution scanning electron microscope at multiple length-scales: nanoindentation for understanding interfacial stress-transfer, micropillar compression and microbeam bending to examine altered plasticity and crack propagation pathways due to nanotubes, and tensile testing to correlate bulk stress-strain response with deformation mechanisms. Real-time imaging shows an interplay of deformation mechanisms, such as nanotube re-alignment, crack-bridging, crack-deflection, nanotube-sliding and pull-out. These mechanisms have the net effect of significantly enhanced elastic modulus (two-fold improvement) and strength (400% enhancement), attesting the suitability of BNNT as a promising nanofiller to engineer advanced nanocomposites. |