Effect of molybdenum addition on structure and properties of high carbon Fe3Al based intermetallic alloy

The effect of molybdenum addition on structure and properties of high (0.3 wt.%) carbon Fe3Al based intermetallic alloy containing about 16 wt.% aluminium has been studied. Three different alloys with the following compositions Fe–16.3 wt.% Al–0.27 wt.% C, Fe–16 wt.% Al–2.85 wt.%, Mo–0.3 wt.% C and Fe–15.8 wt.% Al–7.5 wt.% Mo–0.3 wt.% C were prepared by a combination of air induction melting with flux cover (AIM) and electroslag remelting (ESR). The alloys were characterized with respect to microstructure. Micro-analysis was carried out by electron probe microanalyser. A considerable amount of solid solubility for molybdenum was observed in the carbon containing Fe3Al alloy. At low (2.85 wt.%) concentration of Mo, Fe3AlC0.5 precipitates with dissolved Mo and a small fraction of fine Mo2C precipitates was observed. At a high (7.5 wt.%) concentration of Mo, Fe3AlC0.5 precipitates were totally absent and only Mo2C precipitates were observed. Significant improvements in strength on the addition of Mo has been achieved. This may be attributed to both solid solution strengthening and precipitation hardening.