Investigation on the mechanical properties of nanocrystalline Ni–W alloy with segregated GBAZ

With the help of molecular dynamic simulations, the influence of nickel (Ni) atomic addition, added in the grain boundary affect zone (GBAZ), and tensile strain rates on the mechanical properties of nanocrystalline Ni-doped W (tungsten) alloy is investigated in this paper. The simulation results indicate that Ni atomic fraction plays a crucial part in the mechanical behaviors. The yield stress is proportional to the increase of Ni atomic fraction for δ = 3 Å, indicating a strengthening with the addition of Ni. While for δ = 15 Å, the yield stress is inversely dependent on the increasing addition of Ni. The content of FCC, representing the phase transition in the NC Ni–W alloy, is inversely proportional to the atomic fraction of Ni, with δ = 3 Å. While it grows with the increasing Ni atomic fraction, with δ = 15 Å. More phase transition contributes to weaker tensile strength. This conclusion is well consistent with the tendency of stress versus Ni atomic fraction. Besides, it is worth noting that the eutectic structure is occurred for Ni–W alloys with 60% Ni atomic fraction. The strain rate investigation reveals that higher strain rate would delay the yield strength and dislocations activities perform more intensive under low strain rate.