Preparation, Structure and Properties of Mg-based Bulk amorphous and nanocrystalline nano-materials

摘要

The paper prepares Mg-based bulk metallic amorphous and nanocrystalline nano-materials -Mg_(65)Cu_(25)Y_(10)- by acoustic frequency induction melting and rapid quenching in quartz glass tube. Making use of X-Ray diffraction (XRD), Environmental scanning electron microscopy (ESEM), Transmission electron microscopy (TEM), Atomic force microscopy (AFM), Electron probe microanalysis (EPMA) and so on, it is proved that the sample cooled by liquid nitrogen is mainly composed of amorphous matrix and a little trees dendritic as well as a little deposited nano-crystal. The glass forming ability (GFA) of Mg_(65)Cu_(25)Y_(10) system is quite large. Microcosmicly, the matrix is composed of disperse amorphous structure, while the matrix amorphous phases and the nano-crystal phases deposited among amorphous structures form a kind of special structure of "peritectic". In some areas of the sample's surface whose cooling rate is not enough, there is visible crystallization phenomenon, forming trees dendrite structure. The composition of amorphous parts is near the composition of the mother alloy and the distribution of Mg, Cu and Y is very uniform, which is similar to the glassy state structure; while the element of Mg, Cu or Y clusters in the crystal phase to form intermetallic compound. However, the parallel Mg-Zn-Y system has low glass forming ability, in whose samples there is obviously no amorphous structure formed.