Microstructure and mechanical behaviour of nano-eutectic Fe83B17 alloy prepared by a self-propagating high temperature synthesis combining rapid solidification

摘要

The limited room temperature ductility of nanostructured materials with uniform grain size distribution restricts practical applications. To circumvent this problem, we employ a self-propagating high temperature synthesis combining a rapid solidification process to prepare the bulk nano-eutectic Fe83B17 alloy, which can lead to simultaneous high strength and large ductility. The microstructure of the Fe83B17 alloy has been examined in detail using x-ray diffraction, scanning electron microscopy and transmission electron microscopy. The Fe83B17 alloy is composed of the eutectic of tetragonal Fe2B and alpha-Fe phases. The t-Fe2B and alpha-Fe phases display a fine lamellar eutectic structure with lamellar spacing of about 50 nm. The size of the eutectic colonies is in the range 3-25 mu m. High yield strength (1089MPa) and large ductility (similar to 24.9%) are observed simultaneously in mechanical behaviour tests. The rotation of the eutectic colonies, accompanying viscosity plastic flows to release the localization of the shear stress, can contribute to the simultaneous high strength and large ductility.