Processing of iron aluminides

A processing route comprising of air induction melting (AIM) with protectiv e cover and electroslag remelting (ESR) for production of iron aluminide (F e3Al) alloys has been developed. The use of protective cover during AIM res ults in the minimization of hydrogen gas porosity and a significant reducti on in the impurity levels (S, O and N). Attempts have been made to further improve the ductility and hot workability through ESR. The AIM melted with high carbon ingots exhibit excellent tensile properties compared to the low (< 0.074 wt.%) carbon ingots where cracks persist even after ESR. Processi ng maps were developed for vacuum induction melted as-cast binary and terna ry (Cr and Mn) Fe3Al alloys. Processing maps of Fe3Al and Fe3Al-Cr exhibit a dynamic recrystallisation domain at temperatures > 1123 K. Dynamic recrys tallisation in iron aluminides is controlled by migration of interfaces. In the case of Fe3Al-Mn, dynamic recrystallisation is suppressed due to great er resistance to the migration of interfaces. Instead, large grain superpla sticity is observed. (C) 1998 Published by Elsevier Science S.A. All rights reserved.