Investigation Of Radiation Damage In Fe-Ni Nanoscale Multilayers And Corresponding Bulk Metals Based On Molecular Dynamics

Materials in the extreme irradiation environments introduced by the advanced nuclear reactor systems will have critical damages such as swelling, embrittlement, and accelerated creep, which are known as the mainly threatens of the stability of material mechanics properties and important inducing factors of the reactor materials failure. Hence, the development of the ultrahigh radiation tolerance materials and the exploration of material’s radiation damage mechanism are of primary importance in achieving the goal of improving our advanced nuclear reactor technology. In this paper, we investigated the radiation damage in Fe-Ni nanoscale multilayers and corresponding bulk metals with different interface orientation relationships and lattice configurations based on molecular dynamics. The typical contents and conclusions are summarized as follows:1) The defect evolution in Fe and Ni bulk metal materials with different lattice configurations were simulated when irradiated by PKA with energy of 1-10 ke V at 100 K temperature. Results indicated that the number of displacements, that is frenkel pairs, increases and reaches a peak and then decreases to a constant value. The number of maximum and final stable defects increase, and the time taken by defect number peak formation is extended with increasing of PKA energy. A higher PKA energy aggravates cascade collision. When Fe or Ni bulk metal material with different lattice configurations irradiated by PKA with the same energy, the defects number varied very little, which indicated that lattice configuration hardly influence radiation damage of Fe or Ni bulk metal material. The displacement threshold of Ni atom is bigger than Fe atom’s, causing less displacement probability of Ni atom, so the Fe bulk metal material has serious radiation damage than Ni bulk metal material when irradiated by PKA with same energy.2) By using molecular dynamics code Lammps, we established the Fe-Ni nanoscale multilayers with KS, NW, Bain, and Pistch interface orientation relationships(ORs). Then the Fe-Ni nanoscale multilayers with different ORs were irradiated by PKA with energy of 1-10 ke V at 100 K temperature. To determine how these interfaces influence radiation damage, we should focus on two aspects: the damage in bulk region(the region on both sides of the interface) and the interface damage after PKA injection. The defects number in the bulk region of these nanocomposites was fewer than in the Fe or Ni bulk metal materials whether during the process or in their final state. That indicated the KS and NW OR nanocomposites had better radiation tolerance than Fe and Ni bulk metal materials. Atoms in the NW interface were much tighter and the proportion of dislocated atoms was smaller in the NW interface than other interfaces.Through comparing the defects number in the bulk of nanoscale multilayers, indicated no relationship between interface ORs and bulk defects number.We studied the radiation damage in Fe-Ni nanoscale multilayers and Fe, Ni bulk metal material. The researches will be helpful for the investigation of radiation damage resistance material. Furthermore, it also lays a theoretical foundation for developing nanoscale multilayers composing of element Fe.