Dissociation of super-dislocations and the stacking fault energy in TiAl based alloys with Nb-doping

Dissociations of super-dislocations in γ-TiAl in Nb-doped Ti-48 at.% Al-1 at.% Nb and Ti-48 at.% Al-10 at.% Nb have been studied by high resolution transmission electron microscopy (HRTEM) and weak beam transmission electron microscopy (TEM). The SISF energy was calculated to be 63 mJ/m2 in Ti-48 at.% Al-1 at.% Nb and 34 mJ/m2 in Ti-48 at.% Al-10 at.% Nb according to the dissociation width, respectively. Consequently, it is concluded that Nb-addition can decrease the SF energy significantly, which contribute obviously to the strengthening effect induced by Nb-doping.