Thermal stability and elevated temperature mechanical properties of electroslag remelted Fe-16wt.%Al-(0.14–0.5)wt.%C intermetallic alloys

Abstract

Addition of carbon in the range of 0,14–0.5 wt.% to the Fe 3Al-based intermetallic Fe-16wt.%Al (Fe-28at.%Al) alloy results in the formation of a thermally stable dispersion of Fe,AIC carbide phase. The volume fraction of these precipitates increases with increase in carbon content. Processing of these alloys through a combination of air induction melting and electroslag remelting leads to enhanced elevated temperature mechanical properties compared to those reported for the low (< 0.01 wt.%) carbon alloys with similar Al contents. Enhancement of up to 30% in elevated temperature yield strength was observed at the test temperatures (600, 700 and 800°C) used. The improvement in mechanical properties may be attributed to the presence of strengthening Fe 3AlC phase as well as the interstitial carbon present in the alloy matrix. The addition of carbon also leads to improved room temperature mechanical properties in contrast with other alloying additions (such as Mo, Ti and Si) used for enhancing elevated temperature properties of Fe 3Al-based intermetallic alloys. It is suggested that carbon may be an important alloying addition to these alloys.