The mechanical properties and deformation mechanism of coaxial polycrystalline Ni with different misorientation angles (MA) under tensile load are simulated by molecular dynamics, focusing on investigating the activation mechanism of 111 partial dislocation slip systems. It was found that under fixed load stress conditions, the orientation of grains is determined by the MA value, and the Schmid factor (SF) value also changes accordingly. The activation of dislocation slip systems is regulated by MA and SF, where the dislocations exhibiting lower MA and higher-SF values are preferentially activated. This activated dislocation slip system not only induces the nucleation and growth of stacking faults, but also facilitates stress transmission, further promoting the activation of other partial dislocations. Specifically, the polycrystalline Ni with a rotation angle of 50° exhibited the highest tensile strength and plastic deformation ability. The Lomer–Cottrell (L-C) locks formed by the interaction of partial dislocations from different slip systems or L-C locks due to the partial dislocations blocked by stacking faults, combined with the broadening of stacking faults by energy absorption, jointly strengthen polycrystalline Ni materials. These insights provide a data foundation and theoretical basis for the design and development of polycrystalline nickel for high-temperature alloys.
Zhang et al. (Sat,) studied this question.