Molecular Dynamics Simulation Of Ni₃Al Deformation Under Tension/Compression

Single crystal is an essential component of both coarse-grained materials, nanocrystalline materials and nano-devices, it is of great significance to study the mechanical behavior of single crystal. Therefore, the study of Ni3Al single crystal is the foundation for researching defects, deformation behavior and micro-deformation mechanism of Ni3Al. In this paper, molecular dynamics simulation is used to study the deformation behavior of single crystal Ni3Al bulk under uniaxial tension/compression. We discuss the mechanical behavior and deformation mechanism at different temperatures, sizes and crystal orientation conditions. The main results include:1.The yield stress of Ni3Al nano-bulk exhibit obvious tensile/compression asymmetry, and of great dependent on crystal orientation:when the crystal is on [100] [010] [001] orientation, the tensile strength is stronger than compressive strength, and the dislocation slips on {111} <110> slip system; when the crystal orientation is [100][011][011], the compressive strength is stronger than tensile strength, and the slip system is {111} <112>; when the crystal orientation is [111][112][110], there comes the strongest tensile/compression asymmetry, the compressive strength is much higher than the tensile strength.2.Tension or compression yield strength of nano-bulk Ni3Al decreases with increasing temperature. But under tention conditions, the strain energy of Ni3Al are not sensitive to temperature change, which is unlike the significant change in the compressive condition.3.Size effect on the yield strength of nano-bulk Ni3Al tension/compression is obvious. Tension (compression) yield strength decreased with the increase of model size, which is caused by the weakening of surface effects.