三种M_3Al型金属间化合物的低温热腐蚀

HOT CORROSION OF THREE M_3Al-TYPE INTERMETALLICS AT 600℃

Na_2SO_4沉积物显著地加速Fe_3Al、Ni_3Al和Ti_3Al在600℃模拟燃气气氛中的腐蚀.腐蚀产物为M与Al的氧化物和硫化物的混合物.

Na_2SO_4 deposits accelerate significantly the corrosion rates of 3 intermetallicsFe_3Al, Ni_3Al and Ti_3Al in the simulated combustion gases at 600℃. The corrosion product ismixture of oxides and sulphides of both the base metal and Al. Corrosion resistance of Fe_3Aland Ti_3Al is superior to that of Ni_3Al owing to the formation of an inner layer rich inAl_2O_3 for Fe_3Al and of an intermediate layer composed of TiO_2 and NbO_2 for Ti_3Al modi-fied by Nb. While, Ni_3Al forms an inner layer which is so abundant in Ni sulphide as to facili-tate the migration of Ni outward. The addition of NaCl to Na_2SO_4 has no significant influ-ence on the corrosion behaviour of the three intermetallics.