Studies on preparation, characterisation and evaluation of properties of Fe3Al-based intermetallic alloy of composition Fe-16Al-5.44Cr-1Nb-0.5C

Efforts on preparation of iron aluminide-based (Fe3Al) alloys by various te chniques are being explored worldwide in view of their excellent combinatio n of metallurgical properties suitable for high temperature applications. S o far no process has yet emerged suitable for its commercial exploitation. In the present investigation, an attempt has been made to prepare Fe3Al-bas ed alloy (iron aluminide alloy) of composition Fe-16Al-5.44Cr-1Nb-0.5C (wt. %) by non-conventional non-furnace process. The process essentially involve s the use of cheap, indigenously available oxides of iron, chromium and nio bium for their co-reduction with large excess of aluminium, in presence of carbon under flowing argon atmosphere in a specially designed water cooled copper reactor. The charge composition is judiciously adjusted to fulfil tw o functions simultaneously. Firstly, to attain the alloy composition and se condly, to utilise exothermicity of the overall reactions for their success ful completion. A typical charge constituting At 10 wt.% over stoichiometri c amount, Cr2O3 stoichiometric amount, Nb2O5 and C, double the requisite th eoretical amount and lime (CaO) 10 wt.% of total charge (specific heat, 293 0 kJ kg(-1)) resulted in an alloy of nearly targeted composition with about 98 wt.% yield. The alloy formation by the above technique is substantiated by studies on alloy characterisation with respect to composition, phases a nd microstructure and property evaluation by strength, hardness, rolling an d oxidation resistance to indicate its suitability for high temperature app lications. (C) 2001 Published by Elsevier Science B.V.