The Effects of Grain Boundary Misorientation on the Mechanical Properties and Mechanism of Plastic Deformation of Ni/Ni3Al: A Molecular Dynamics Study

The effects of grain boundary misorientation angle (θ) on mechanical properties and the mechanism of plastic deformation of the Ni/Ni₃Al interface under tensile loading were investigated using molecular dynamics simulations. The results show that the space lattice arrangement at the interface is dependent on grain boundary misorientations, while the interfacial energy is dependent on the arrangement. The interfacial energy varies in a W pattern as the grain boundary misorientation increases from 0° to 90°. Specifically, the interfacial energy first decreases and then increases in both segments of 0–60° and 60–90°. The yield strength, elastic modulus, and mean flow stress decrease as the interfacial energy increases. The mechanism of plastic deformation varies as the grain boundary misorientation angle (θ) increases from 0° to 90°. When θ = 0°, the microscopic plastic deformation mechanisms of the Ni and Ni₃Al layers are both dominated by stacking faults induced by Shockley dislocations. When θ = 30°, 60°, and 80°, the mechanisms of plastic deformation of the Ni and Ni₃Al layers are the decomposition of stacking faults into twin grain boundaries caused by extended dislocations and the proliferation of stacking faults, respectively. When θ = 90°, the mechanisms of plastic deformation of both the Ni and Ni₃Al layers are dominated by twinning area growth resulting from extended dislocations.