| Abstract Scope |
Nanocrystalline high entropy alloys (HEAs) offer superior mechanical properties but suffer from rapid grain coarsening at elevated temperatures. This study investigates the thermal stability of mechanically alloyed AlCoCrCuFeNi doped with 1 at.% Boron, Yttrium, or Zirconium. While the base alloy coarsened significantly at 1173 K (about 0.75 Tm), doped variants retained nanocrystalline structures. Boron proved most effective, stabilizing a grain size of 17 nm, followed by Zirconium at 27 nm, and Yttrium at 31 nm. XRD, TEM, and Molecular Dynamics simulations confirmed that dopant segregation to grain boundaries provides thermodynamic stabilization. Consequently, the doped alloys retained over 80% of their as-milled hardness, with values ranging from 8.56 to 8.95 GPa, validating minor solute doping as a viable pathway for developing thermally stable HEAs. |