Plasma-nitriding and characterization of FeAl40 iron aluminide

The response to plasma-nitriding of a B2 FeAl40 aluminide was investigated in this work using varying temperatures, times and gas mixtures. The microstructure of the plasma-nitrided cases were fully characterized using glow discharge optical emission spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray diffraction and transmission electron microscopy, as well as microhardness testing. Based on the experimental results, the observed abnormal growth kinetics of the nitride case formed at 700 °C was investigated and a model was put forward to understand the mechanism involved in the formation of wave-like line features within the nitride cases.