gamma <->alpha(2) phase transformation in fractured high temperature stress rupture Ti-48Al-2Nb(at.%)

The gamma <----> alpha(2) phase transformation in fractured high temperatur e stress rupture Ti-48Al-2Nb(at.%) alloy has been studied by analytical ele ctron microscopy. alpha(2) and gamma phases were found at grain boundaries. alpha(2) layers that suspended in gamma layers and interfacial ledge highe r than 2d((111)gamma) at gamma/alpha(2) interfaces were observed in the lam ellar grains. These facts indicated that gamma <----> alpha(2) phase transf ormation and dynamic recrystallization have occurred during high temperatur e stress rupture deformation. It can be concluded that deformation induced gamma <----> alpha(2) phase transformation and dynamic recrystallization re sulted in the presence of gamma particles at grain boundaries. A structural and compositional transition area between deformation-induced alpha(2)(or gamma) and its adjacently original gamma(or alpha(2)) phases was found by H REM and EDS and is suggested as a way to transform between gamma and alpha( 2) phase during high temperature stress rupture deformation. The transition area was formed by slide of partial dislocations on close-packed planes an d diffusion of atoms. (C) 2000 Kluwer Academic Publishers.