Structural and Mechanical Behaviour of Al-Fe Intermetallics

Abstract

In this chapter, results of our recent investigations on Al-25%Fe (at.%), Al-30%Fe and Al-34.5%Fe alloys close to Al3 Fe, Al5 Fe2 and Al2 Fe intermetallic phases have been discussed. The efect of process parameters on structural aspects and mechanical behaviour of Al-Fe intermetallics has been studied. The high melting intermetallics that are diicult to prepare by conventional processing technique are easily synthesized in nanocrystalline state with a homogeneous structure by mechanical means. In this process, we have come out with a single orthorhombic Al5 Fe2 nanocrystalline intermetallic phase. Hardness measurements of intermetallic revealed an increase in hardness with a decreasing grain size up to a critical grain size, followed by a decrease. A decrease in hardness with a grain size reinement, an indication of softening behaviour, demonstrating the Inverse Hall-Petch (IHP)-like phenom- enon has been observed in intermetallic compounds. The deviation from the regular Hall- Petch (HP) behaviour has been discussed using various deformation models based on the dislocations and grain boundary-mediated processes. The study is focused on investigations of Al-rich iron aluminide intermetallics to understand the structure property correlations.