First-principles study on the effects of Er/Hf ratio on the properties of L12-Al3(Er,Hf)

Abstract

L12-structured tri-aluminides in additively manufactured (AM) Al alloys refine α-Al grains while playing a significant role in precipitation strengthening. To precipitate the tri-aluminide dispersoids with an improved nucleation efficiency and coarsening resistance in AM Al alloys, the joint addition of Er and Hf into Al is proposed to form ternary L12-Al3(Er,Hf) precipitates. The work applies the first-principles method of projected augmented wave (PAW) under the framework of density functional theory (DFT), to calculate the lattice constant, formation energy, binding energy, bulk modulus, and density of states of L12-Al3(Erx,Hf1-x) (x = 0, 0.25, 0.5, 0.75, 1). The effects of Er/Hf ratios on certain key properties and features of the L12-Al3(Er,Hf) compounds and an Al alloy that contains the compounds are discussed.