APFIM STUDY OF BETA-MICRODUPLEX AND GAMMA-MICRODUPLEX TIAL INTERMETALLIC ALLOY

beta and gamma microduplex TiAl intermetallic alloy prepared by thermo mechanical processing was characterized by atom prove field ion micros cope (APFIM) in atomic level. TEM-SAD observation revealed B2 ordering in the beta-phase, while its ordering is expected to be not so high f rom its composition analysis result and the high temperature deformati on mechanism of this alloy. The compositions for each phase determined by APFIM are in good agreement with those determined by TEM-EDX other than the Cr distribution in the beta-phase. However, Cr site occupanc y was not determined in the gamma-phase due to a failure in analyzing the ladder diagram probably caused by this materials intrinsic evapora tion behavior. Small amounts of ions probably due to oxygen were detec ted in beta, not in gamma, providing a speculation of oxygen scavengin g from the gamma-phase. Hydrides were detected in both the gamma- and beta-phase. (C) 1997 Elsevier Science S.A.