Interactions between Lattice Dislocations and Grain Boundaries in Ni3Al Investigated by Means of In Situ TEM and Computer Modelling Experiments

The interaction between lattice dislocations and grain boundaries in Ni3Al has been investigated by means of in situ TEM deformation experiments. The interaction between screw dislocations and a coherent twin boundary could be analyzed in detail. The interaction mechanism found experimentally was compared to the results of a computer modelling study. In the computer modelling study, many-body potentials representing Ni3Al were used. The results of the in situ straining indicate that <110> screw dislocations impinging on a Σ = 3 coherent twin boundary that have a Burgers vector that is parallel to the grain boundary plane can be transmitted to the symmetric slip plane in the other grain under influence of an applied stress. A one-to-one comparison with the results of a computer modelling study of exactly the same system in Ni3Al can be made and the experiment agrees with the simulations. Also, observations were made of superlattice intrinsic stacking faults (SISF) that were formed as a result of the interaction between gliding dislocations and the dislocations of a low angle grain boundary (cell wall). The creation of jogs in the line of the gliding dislocation may be the cause of the SISF formation