HIGH-TEMPERATURE CORROSION BEHAVIOR OF IRON ALUMINIDES CONTAINING TERNARY ADDITIONS IN H-2 H2S/H2O MIXED GASES/

The high-temperature corrosion behavior of four iron aluminides contai ning Fe-18Al (in at.%) and three Fe-18Al-5M alloys (where M was Cr, Mn , or Mo) was studied over the temperature range of 700-900 degrees C i n a H-2/H2S/H2O atmosphere. The corrosion kinetics followed the parabo lic rate law in all cases, regardless of temperature and alloy composi tion. The parabolic rate constants decreased with decreasing temperatu re, and the addition of ternary elements resulted in various decreases in the corrosion rate compared with Fe-18Al. It was found that Mo was effective to improve the corrosion resistance at T equal to or less t han 800 degrees C while Cr had a better improvement at 900 degrees C. The scales formed on all iron aluminides were strongly dependent on te mperature and ternary addition. (C) 1997 Elsevier Science S.A.