Sulfur-impurity induced amorphization of nickel

Recent experimental and theoretical studies have shown an essential role of sulfur segregation-induced amorphization of crystalline nickel leading to its embrittlement at a critical sulfur concentration of ∼14, but the atomistic mechanism of the amorphization remains unexplained. Here, molecular dynamics simulations reveal that the large steric size of sulfur impurity causes strong sulfur-sulfur interaction mediated by lattice distortion up to the next nearest-neighbor lattice sites and that amorphization occurs at the percolation threshold of the sulfur-sulfur network with the next nearest-neighbor connectivity. Furthermore, the generality of the amorphization mechanism due to the percolation of an impurity network is confirmed for a model binary material. © 2011 American Institute of Physics.