Molecular dynamics simulation on shear mechanical properties of single crystal/polycrystalline Ni composites

The integral blisk technology has been used to connect single crystal Ni turbine blades and polycrystal Ni discs with different performances into an integral blisk, but it has brought a high-risk failure problem in the joint area of the blisk, which seriously restricts the development of the technology. The shear mechanical properties of single crystal/polycrystalline Ni composites were studied by the molecular dynamics method. Firstly, the influence of crystalline state on the shear mechanical properties was discussed. Then, the effects of shear rate and temperature on the shear mechanical behavior of the single crystal/polycrystalline Ni composites were examined. The results show that, compared with single crystal Ni, the overall shear stress of single crystal/polycrystalline Ni composites decreases due to the addition of polycrystalline Ni. The shear strength of the single crystal/polycrystalline Ni composites is significantly smaller than that of single crystal Ni. After the shear deformation of the different crystalline Ni enters the plastic state, a phenomenon similar to that of macroscopic material necking occurs, and the atoms near the necking zone are locally dislocated, rearranged, and partially amorphized. The shear modulus of the single crystal/polycrystalline Ni composites increase with the increase of shear loading rate, while they shows a downward trend with temperature rising. © 2020, Science Press. All right reserved.