Fracture of Fe95Ni5 Alloys with Gradient-Grained Structure under Uniaxial Tension

Abstract

The fracture behavior of single- (fcc) and two-phase (fcc + bcc) Fe95Ni5 samples with gradient-grained structure, under uniaxial tension, was analyzed via molecular dynamics simulation. The study revealed that fracture initiation and propagation is always associated with grain boundaries. The fracture process develops in three stages. In the first stage, nanopores are formed in the boundaries of coarse grains. The total volume of nanopores at this stage increases slowly due to the formation of new nanopores. The second stage is characterized by a rapid increase in the total nanopore volume due to the formation of nanopores, their growth along the grain boundaries, and their coalescence. At the third stage, the total nanopore volume increases linearly with deformation due to the growth of the largest nanopores. Fracture of two-phase samples begins at higher strains compared to a single-phase sample. With an increase in the volume fraction of bcc lamellae in the original sample, the number of nanopores at the third stage of fracture decreases and tends to one.