ABSTRACT
Owing to recent progress in nanotechnology, the ability to tune the surface properties of metals has opened an avenue for creating a new generation of biomaterials. Here we demonstrate the successful development of a novel Ti-based nanoglass composite with submicron-nanometer-sized hierarchical glassy structures. A first exploratory study was performed on the application of the unique nanostructure to modulate osteoblast behaviors. Our results show that this Ti-based nanoglass composite, relative to conventional metallic glasses, exhibits significantly improved biocompatibility. In fact, a 10 times enhancement in cell proliferation has been achieved. To a great extent, this superior bioactivity (such as enhanced cell proliferation and osteogenic phenotype) is promoted by its unique hierarchical structures combining nanoglobules and submicron button-like clusters from collective packing of these nanoglobules. This nanoglass composite could be widely applicable for surface modifications by means of coating on various materials including BMGs, crystalline metals or ceramics. Therefore, our successful experimental testing of this nanostructured metallic glass may open the way to new applications in novel biomaterial design for the purpose of bone replacement.
ABSTRACT
Effect of electron irradiation on stability of nanocrystallites dispersed in a glassy matrix of a Cu50Zr45Ti5 bulk metallic glass (BMG) alloy was investigated. Microstructural evolution during electron irradiation was observed and analyzed by means of conventional and high-resolution transmission electron microscopy (CTEM and HRTEM) and X-ray energy dispersive spectroscopy (EDS). The crystalline nanoparticles of monoclinic CuZr phase formed in-situ in as-cast Cu50Zr45Ti5 alloy exhibited a high stability against electron irradiation. No obvious changes in their size, morphology, and crystal structure were observed during electron irradiation, though new crystalline nanoparticles nucleated and precipitated in the glassy matrix under electron irradiation. The new nanoparticles formed upon irradiation have a similar composition and crystal structure to those formed in-situ in the as-cast alloy. The nanocrystalline precipitates in the glassy matrix are proposed to be mainly due to electron knock-on effect under electron irradiation, which promotes atomic diffusion and assists the crystallization of the glassy phase. The present result indicates that electron irradiation to metallic glasses has potential for producing nanocrystalline structure and nanocrystalline-glassy composite structure.
