Influence of Sintering Temperature on the Structure and Properties of Powder Iron Aluminide Fe3Al

Abstract

The paper examines the impact of heating temperature and isothermal holding time during sintering in a vacuum on the phase composition, structure, and mechanical properties of Fe3Al iron aluminide synthesized from a mixture of iron and aluminum powders. Dilatometric studies have shown the complexity of occurring changes in the density of the billets during sintering. First, the porosity increases from 15% in the initial billet to 45% during sintering at 950°C, and after decreases to 5% at a sintering temperature of 1450°C. The synthesis of intermetallic compounds at powder mixture heating was examined by the X-ray diffraction method. It was shown that up to 30% of intermetallic compound Fe2Al5 is formed during an hour-long isothermal holding at 600°C. Increasing the holding time to 3 hours or temperature to 950°C results in the formation and gradual growth of FeAl (B2) aluminide content. With a further increase of sintering temperature up to 1450°C, the amount of A2 phase becomes bigger, and concentration of iron and aluminum in it approaches to stoichiometric ratio Fe3Al. The mechanical properties of iron aluminide intensify with increasing sintering temperature, especially rapidly after sintering at 1450°C, when planar pores close and perfect interparticle contacts form.