ELECTROLYTIC ISOLATION AND QUANTITATIVE-DETERMINATION OF ALPHA(2) ANDNONMETALLIC PHASES IN GAMMA-TIAL BASE ALLOYS

An electrolytic isolation of the alpha(2) and non-metallic phases in g amma-TiAl-base alloys was tried, aiming at quantitative determination of the amounts of these phases in the alloys. The amount of electrolyt ic residue increased with increasing the oxygen content of the gamma-b ase alloys with the same levels in both Al and nitrogen contents. The amount of the alpha(2) phase determined by electrolytic isolation was significantly smaller than that determined by microstructure observati on, except in the case of Ti-52.7at%Al with 0.01 mass% oxygen and nitr ogen. In conclusion, the electrolytic isolation is especially useful i n the determination of small amounts of the alpha(2) and non-metallic phases in Al-rich gamma-TiAl-base alloys, but some corrections are nee ded in the alloys with Al concentrations of 50 at% or less.