Configuration of superdislocations in the γ′-Pt3Al phase of a Pt-based superalloy

The configuration of superdislocations in the γ′-Pt3Al phase of a Pt-based superalloy after high temperature tensile creep deformation is evaluated. Weak-beam dark field transmission electron microscopy is used to measure dissociation width of superdislocation partials. Short, straight segments of dissociated dislocations with 〈110〉-type Burgers vectors are observed. Dissociation takes place on {111} planes with a separation of the partials in-between 3.4 and 4.5 nm, resulting in antiphase boundary energies of 344-456 mJ/m2 considering elastic anisotropy. The dislocations are of mixed edge and screw type character and are in planar configuration. First-principles antiphase boundary energy calculations in stoichiometric Pt3Al reveal that the energy of {111} boundaries is 205 mJ/m2, the {010} energy 414 mJ/m2.