A Study on the Mechanical Properties of Ni-Al Alloy Based on Molecular Dynamics Simulation

With the wide application of Ni-Al high-temperature materials, the research on their performance has increasingly attracted attention. To further advance the development of Ni-Al high-temperature materials, it is necessary to conduct an in-depth analysis of the brittleness mechanism of Ni-Al intermetallic compounds and elucidate the fundamental nature of their brittleness. In this study, the tensile mechanical behavior and microscopic mechanism of single crystals NiAl (B2) and Ni3Al (L12) at different temperatures were systematically studied by molecular dynamics simulations. It is revealed that although the mechanical properties of both NiAl and Ni3Al degrade with increasing temperature, their deformation mechanisms exhibit fundamental differences. The high-temperature strength of NiAl is attributed to stable plastic flow dominated by 1/2 <111> screw dislocation. The early softening of Ni3Al is associated with the formation of stacking fault formation, the phase transition to the HCP, and the slip of various incomplete dislocations (e.g., 1/6 <112> Shockley dislocation). Atomic strain analysis shows that regions of high strain exhibit a strong spatial correlation with the phase-transformed domains. This study reveals the distinct deformation mechanism of the two alloy phases at the atomic scale, providing a key theoretical basis for the rational selection of Ni-Al alloy in specific high-temperature applications.