Microstructure and mechanical behaviour of nano-eutectic Fe ₈₃B₁₇ alloy prepared by a self-propagating high temperature synthesis combining rapid solidification

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 Fe ₈₃B₁₇ 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 Fe₈₃B ₁₇ alloy is composed of the eutectic of tetragonal Fe₂B and α-Fe phases. The t-Fe₂B and α-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 νm. High yield strength (1089 MPa) and large ductility (∼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.