Weak-beam TEM study on planar fault energies of Al-lean TiAl-base alloys

Weak-beam transmission electron microscope (TEM) analyses of 1/2<112> superdislocations were performed in order to determine the stacking fault energies in Ti-45Al, Ti-49Al, Ti-45Al-10Nb and Ti-49Al-10Nb alloys (at.%) at 900 degreesC. In Al-lean binary TiAl alloys, the SISF energies decrease significantly with decreasing Al concentration in the gamma phase, from 97 mJ m(-2) for 49.6% Al to 64 mJ m(-2) for 48% Al. The ternary alloys exhibit a relatively low SISF energy of about 68 mJ m(-2), which is practically independent of the Al concentration. (C) 2002 Elsevier Science B.V. All rights reserved.