(525f) Using Shape Anisotropy to Toughen Disordered Particle Assemblies

Disordered solids constitute an important class of materials that find wide-ranging applications from energy devices to bone replacement. A major roadblock limiting the widespread utilization of these amorphous materials is their tendency to undergo mechanical failure under small load. The fundamental understanding on their mechanical behavior is imperative for the development of new strategies to enhance their mechanical properties (hardness, modulus, and fracture toughness). In our work, we study the effect of particle shape anisotropy on the mechanical behavior of disordered nanoparticle packings. We study the mechanical response of disordered nanoparticle packings made of TiO₂ prolate ellipsoids with various aspect ratios using nanoindentation. We observe striking similarities in the deformation mechanism of disordered particle assemblies to that of metallic glasses, which are random packings of metallic atoms. It is demonstrated that anisotropic particles greatly suppress shear band formation and toughen particle packings without sacrificing their strength, which implies that tuning constituent-anisotropy may be a new strategy to enhance toughness in disordered solids.