High-temperature corrosion behaviours of nickel–iron-based alloys with different molybdenum and tungsten contents in a coal ash/flue gas environment

Abstract High-temperature coal ash/flue gas corrosion behaviours of three nickel–iron based superalloys for boiler tubes with different Mo and W contents (1.8% + 1.2% S 1 alloy, 0.8% 0.2% 2 0.5% 2.2% 3 alloy) at 650 700°C were studied. The microstructure, phase compositions, morphologies together element distribution products investigated a metallographic microscope, scanning electron microscope equipped an energy-dispersive spectroscope, X-ray diffractometer. results show that the resistance Ni–Fe-based alloy decreases increasing total content in both 700°C; outer layer was mainly composed FeCr O 4 while inner Cr . Peeling oxide films formed on surfaces alloys observed but no obvious spalling alloy. reactions among Mo, W, increased internal stress scale, which would cause failure scale.