Microstructural strengthening by phase transformation in Al-Fe3Al composites

Abstract

Abstract The effectiveness of the reaction between matrix and reinforcement as a strengthening method for further improving the mechanical performance of the Al-Fe 3 Al composites has been investigated. Phase analysis and microstructural characterization of the transformed composites reveal the formation of a double-shell-reinforcement with Al 5 Fe 2 and Al 13 Fe 4 intermetallics surrounding the Fe 3 Al phase, while the Al matrix is progressively consumed with increasing the reinforcement content. The phase transformation during hot pressing induces significant strengthening: the ranges of yield and compressive strengths increase from 70–360 MPa and 200–500 MPa for the non-transformed composites to 400–1800 MPa and 550–1800 MPa for the transformed materials. This occurs at the expense of the plastic deformation, which is generally reduced in the transformed composites. The yield strength of both transformed and non-transformed composites follows the iso-stress model when the characteristic structural features (i.e. strengthening phases and matrix) are taken into account.