Structural, thermal and magnetic investigations on immiscible Ag–Co nanocrystalline alloy with addition of Mn

•A complete solid solution of Ag–Co–Mn alloy obtained after 50 h of milling.•A complete solid solution of milled Ag–Co alloy forms annealed at 350 °C for 1 h.•Precipitation of fcc Co are observed after annealing above 350 °C.•Enthalpy of mixing of the alloys increased with increase in milling time.•The superior magnetic properties achieved of Ag–Co–Mn alloy annealed at 550 °C.

50Ag–50Co (at%) and 40Ag–40Co–20Mn (at%) alloys prepared by ball milling up to 50 h and subsequent isothermal annealing at the temperature range of 350–650 °C for 1 h has been investigated systematically. Mn promotes early formation of the nanostructures and solid solutions of the alloys by ball milling. In contrast, annealing at 350 °C of Ag–Co alloy resulted the dissolution of hcp Co. Annealing above 350 °C decomposes the metastable Ag–Co alloy into the polycrystalline and segregated Ag and fcc Co. Enthalpy of mixing of both the alloy has increased with increase in milling time. Both the nanocrystalline alloys prepared by ball milling and annealing have been revealed the ferromagnetic behavior. The most significant improvement of magnetic properties is yielded in as-milled Ag–Co–Mn alloy obtained after annealing at 550 °C for 1 h.

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