Influence of Y (yttrium) doping on thermal stability of nanocrystalline AlCoCrCuFeNi high entropy alloy
Document Type
Article
Publication Title
Intermetallics
Publication Date
4-2025
Abstract/ Summary
Nanocrystalline AlCoCrCuFeNi high entropy alloy with 1 at. % Y was prepared by mechanical alloying and its microstructural stability was examined up to 1173 K (0.75 Tm). The lattice parameter analysis of the as-milled alloys shows a dual-phase structure, where Cu and Cr are identified as the host lattices for the FCC (0.362 nm) and BCC (0.288 nm) phases, respectively. The effect of Y addition on the microstructural evolution during annealing was studied by X-ray diffraction (XRD), and transmission electron microscopy (TEM). Molecular dynamics (MD) simulation was incorporated to track the atomistic behaviour of Y. Microhardness measurement was utilized to study the ability to retain strength after high temperature exposure. The FCC phase fraction is found to increase monotonically with increase in the annealing temperature. The Y addition helps in stabilizing an average grain size of ∼31 nm after annealing at 1173 K, along with retaining 82 % of the hardness (∼8.56 ± 0.3 GPa) observed for the ball-milled base alloy. The theoretical framework corroborated with the MD simulation elicited that the “thermodynamic” stabilization mechanism controls the superior coarsening resistance of the alloy. The strength predicted by the Hall-Petch analysis is in good agreement with the experimental result, further substantiating the stabilization of the nanocrystalline microstructure in the alloy annealed at 1173 K.