| This paper deals with the problem of using M-A1 series intermetallic compounds as coating materials and the preparation process of intermetallic coatings to avoid its disadvantage of brittleness. The results of experiments show that intermetallic coatings with better using value can be produced with high temperature diffusion process or powder thermal spray process. The microstructure of high temperature diffusion intermetallic coatings is denser and the components of the coatings changed gradually from surface to substrate. The bonding state of the coatings and the substrate is metallurgical bonding. The microstructure and thickness of the coatings changed with the increase of diffusion temperature regularly. Powder thermal spray process has virtues of high efficiency, handling conveniently and the thickness of the coating can be controlled easily. The hardness of Fe-Al or Ni-Al series intermetallic coatings made by the two kinds of process is high and the micro-hardness of some Fe-Al intermetallic coatings is as high as HV0.2l042. After the analysis of Fe-Al phase diagram and the thermo analysis of the forming of FesAl, it can be find that Fe3Al only exists at temperature lower than 551.4℃. When the temperature higher than 551.4℃, the phase of the material would change from Fe3Al to FeAl. The new phase also has excellent oxidation resistance. The high temperature characteristics of FesAl, which were discussed in the past, are that of FeAl behaved in fact. Because of the high hardness and stability of intermetallics, the using of intermetallic coating can enlarge the substrate's serving temperature range and represents excellent resistance to wear and erosion of the coating at high temperature and exhibits high ratio of property & price.
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