Mechanical Behavior and Deformation Mechanism of NiAl Alloy With Gradient Structure by Molecular Dynamics

The contradiction between strength and plasticity in metallic materials has long posed a fundamental challenge for researchers. However, natural biological gradient structures have provided abundant inspiration for addressing this issue. In the present study, molecular dynamics simulations were employed to investigate the effect of gradient structures on the deformation mechanism of NiAl alloys. Research results demonstrate that the Ni 80 Al 20 alloy exhibits superior yield strength coupled with exceptional plastic deformability. Introducing gradient structures into nanocrystalline NiAl alloys reveals that stress fields are primarily accommodated within fine‐grained zones, while dislocation nucleation initiates in coarse‐grained zones followed by progressive propagation and migration toward fine‐grained zones. Owing to the synergistic interaction between the two deformation mechanisms—dislocation motion and grain boundary deformation—gradient alloys exhibit superior strengthening effects compared to coarse‐grained alloys. The positive gradient structure (GY) with fine grains (FG) transitioning to coarse grains (CG) exhibits superior yield strength and flow stress, originating from enhanced grain boundary stability and effective impedance to dislocation slip, which synergistically coordinate deformation mechanisms. The insights into NiAl alloy with gradient structure lay a foundation for the design and development of advanced high‐temperature structural materials.