Response of <110> symmetric tilt grain boundary in titanium nitride under shear

Grain boundaries (GBs) in titanium nitride (TiN) are worth studying since they play a determining role in physical and mechanical properties in nanocrystalline TiN. Using molecular dynamics (MD), we study the structure and shear response of twelve equilibrated and three non-equilibrated TiN (110) symmetric tilt GBs at 300K and 2,400 K. The structure of TiN (110) GB can be well characterized using some simple structure units (SUs). Moreover, the type and number of the SU component in equilibrated TiN GBs are dependent on the tilt angle. It is found that there exist shear coupling and GB sliding deformation mechanisms in TiN GBs. For shear coupling, GB structure keeps intact during shear and GB deformation is predictable by a coupling factor. GB sliding is simply accomplished by a remarkable relative sliding between two grains and may be accompanied by atoms shuffling and nanovoid formation in GB. In addition, GB E3(111) exhibits completely different deformation mechanisms at 300 K and 2,400 K, i.e., the reorientation induced by dislocation nucleation and twinning followed by twin boundary (TB) migration. For non-equilibrated GB states, their deformation mechanisms change from shear coupling to GB sliding.