Effects of Fe content on microstructure and mechanical properties of Al-Y eutectic alloys

This paper describes the main results from an experimental investigation into tailoring the contrasting strengthductility characteristics of an Al-Y eutectic alloy after alloying with Fe. Specimens of Al-6.68Y, Al-6.65Y-0.67Fe, and Al-6.63Y-1.2Fe alloys were cast and studied using several microscopy techniques, in-situ synchrotron X-ray diffraction, and thermodynamic calculations. Microstructural characterization along with thermodynamic calculations revealed that the Al-Y-Fe alloys exhibit fine eutectic structures and increased fraction of eutectic intermetallic phases compared to those in the binary Al-Y alloy. As a result, the Al-Y-Fe alloys showed improved strength and ductility compared to the binary Al-Y counterpart. Furthermore, in-situ synchrotron X-ray diffraction performed on a specimen of the Al-Y-Fe alloy revealed that the additional Al10Fe2Y eutectic intermetallic phase is more deformable than the commonly present plate-like beta-Al3Y eutectic intermetallic phase contributing to strain hardening and ductility improvements of the alloy. Therefore, the optimized strength-ductility combination of the novel Al-Y-Fe alloys, particularly Al-6.65Y-0.67Fe, stem from the plasticity of the Al10Fe2Y intermetallic phase in addition to the refined eutectic structures and increased fraction of the intermetallic phases.