High Temperature Corrosion of Al_3Ti-Cr Intermetallics in an Ar-1 percent SO_2 Gas Atmosphere

摘要

Ll_2-type Al_3Ti-Cr alloys of compositions 67Al-25Ti-8Cr, 66Al-24Ti-10Cr, and 59Al-26Ti-15Cr (in atomic percent) were corrosion tested between 800 deg C and 1100 deg C in an Ar-1 percent SO_2 gas atmosphere for up to 150 h. Corrosion proceeded mainly via oxidation reactions. The scale consisted primarily of a thin Al_2O_3 barrier layer. The alloys tested had much better corrosion resistance than TiAl-base alloys or Hastelloy X. Virtually no sulfides were detected in the scale, because of the strong oxidizing tendency of the Al_3Ti-Cr alloys having high Al concentrations.