First-principle exploration for RE solid-solution influence on Ni mechanical properties

Abstract

Rare earth element (abbreviated as RE) doped nickel alloy is very attracted for the neutron shielding application for excellent neutron absorption and good mechanical behavior. RE solid-solution influence on Ni alloy mechanical properties has been comprehensively investigated by first-principles calculations in this work. The elastic constant and generalized stacking fault energy analysis indicate that RE substitutional solution would decrease the mechanical strength (For example, bulk modulus: BNi = 198.9 GPa, BNi31RE = 174.7 ∼ 189.8 GPa, Young's modulus: ENi = 242 GPa, ENi31RE = 183.1 ∼ 226.1 GPa and shear modulus: GNi = 93.25 GPa, GNi31RE = 69.05 ∼ 86.88 GPa) while increase the plastic deformation (intrinsic stacking fault energy: γis,Ni52 = 137.1 mJ/m2, γis,Ni51RE = 57.69 ∼ 94.17 mJ/m2 and critical intrinsic stress: τcrit,Ni52 = 31.08, τcrit,Ni51RE = 13.89 ∼ 20.00). Furthermore, the influence has a correlation with atomic radii difference Δr/rNi (the bigger difference is, the greater influence is), which is due to that hybridization strength and bonding strength decreases as Δr/rNi increases. The work provide a theoretical guidance for RE doped nickel alloys plastic deformation promotion.