HIGH-TEMPERATURE CORROSION OF DILUTE CHROMIUM LANTHANUM ALLOYS

The kinetics of oxidation in air of chromium-lanthanum alloys have been investigated in the temperature range 1100-1400 degree C. The positive effect of lanthanum on the heat resistance of chromium was established and is explained as a result of the formation of a barrier oxide film consisting of Cr//2O//3 and LaCrO//3. The dispersed particles of lanthanum chromite distributed on grain boundaries form diffusion barriers that change the oxidation law from parabolic to logarithmic. An empirical equation which quantitatively describes mass-transport processes with decreasing effective diffusion area and simultaneous sublimation of scales is proposed.