Mechanical mechanism and deformation behavior of polycrystalline and gradient Ni50−xTi50Alx alloys using molecular dynamics

Abstract

The mechanical response of polycrystalline Ni50−xTi50Alx alloys was studied by using the molecular dynamics (MD) simulation method. The effects of grain size, temperature, and gradient Al content on the material deformation mechanism were investigated. The results revealed that when the grain size was smaller than 80 Å, the stress and the strain in the polycrystalline nanowires tended to concentrate on the grain boundaries. In contrast, in the case of grain sizes larger than 80 Å, dislocation defects dominated the deformation mechanism. In addition, the content of Al atom addition to the Ni50−xTi50Alx alloy exhibits special properties. With Al atoms addition, the ductility of the Ni50−xTi50Alx specimen is increased. Besides, During the uniaxial tensile process, there are stacking fault phenomena exist in the grains. Furthermore, the temperature affected the mechanical behaviors of the alloy as well. The ultimate tensile strength (UTS) values decreased with an increase in the temperature. In the case of temperatures higher than 300 K, the stress concentrated on all the grain boundaries more seriously. In summary, this study provided a systematic research result on the grain size, temperature, and composition of Ni50−xTi50Alx alloys under a uniaxial tensile process via MD simulations.