Tailoring structure, morphology, composition, and magnetism by Ag addition to CoCrFeMnNi-Agx (x = 0; 1; 2.5; 5.5 at. %) high-entropy alloy powders prepared by high-energy ball milling

Nanocrystalline CoCrFeMnNi-Ag x ( x = 0; 1; 2.5; 5.5 at. %) high-entropy alloy (HEA) powders were synthesized for the first time via rapid, two-step high-energy ball milling (HEBM) in Ar. A single-phase fcc Cantor alloy with uniform elemental distribution was obtained after just 60 min of HEBM from an elemental powder blend. Subsequent HEBM for 10 min with Ag addition enabled precise control over Ag distribution and particle morphology, which evolved from flake-like structures with Ag-rich edges ( x = 1; 2.5 at. %) to homogeneous spherical particles ( x = 5.5 at. %). All compositions exhibit paramagnetic behavior at 310 K, with Curie temperatures ( T c ) decreasing from 96 K (Ag-free CoCrFeMnNi) to 71 K (Ag = 5.5 at. %), indicating suppression of magnetic ordering. Importantly, annealing up to 710 K in a magnetic field significantly enhances the magnetic response across all compositions. The CoCrFeMnNi-Ag x ( x = 2.5 at. %) HEA shows the most pronounced improvement, with magnetization ( M ) (9 T, 310 K) increasing 2.5-fold to 16 Am²/kg, coercivity ( H c ) reaching 46 kA/m, and remanence of 4.8 Am 2 /kg. Notably, M approaches ∼ 1/3 of pure Ni under the same conditions, while exhibiting a H c nearly two orders of magnitude higher. These results highlight that Ag alloying and thermal treatment offer an effective approach to tuning magnetic properties in CoCrFeMnNi-based HEAs without compromising structural integrity. The ability to tailor structure, morphology, and magnetism through a scalable route promotes Ag-doped Cantor alloys as promising candidates for multifunctional applications requiring combined structural and magnetic performance.