On the impact toughness of Fe-40Al-based B2 aluminides

Charpy impact tests were conducted in the temperature range 300–973 K on polycrystalline, large-grained Fe–40Al, Fe–40Al-0.6C, and Fe–40Al–0.7C–0.5B alloys that were in the extruded and low-temperature annealed condition. For purpose of comparison, wrought 1045 steel was also similarly tested. At room temperature, the alloy containing carbon and boron exhibited twice the impact resistance of binary Fe–40Al. Impact resistance for all three FeAl-based alloys increased with temperature initially but then exhibited a substantial decrease with further increases in temperature. Fracture mode in the binary FeAl alloy was intergranular at all temperatures whereas in the C-containing alloy, and the C+B alloy, there was some evidence of transgranular cleavage at room temperature; at 973 K a substantial amount of transgranular cleavage was evident. Tensile tests were conducted at a variety of strain rates at room temperature and at 973 K to help understand the impact response observed.