Ferromagnetic behavior of nanocrystalline Cu–Mn alloy prepared by ball milling

• A small amount of Mn has dissolved in Cu after ball milling for 30 h.
• Coercivity of the Cu–Mn alloy has increased with an increase in milling time.
• Substantial MnO has formed after annealing at 650 °C for 1 h.
• The ball milled and annealed alloy have revealed soft ferromagnetic behavior.
• The alloy annealed at 350 °C shows the maximum value of coercivity.

50Cu–50Mn (wt%) alloy was produced by ball milling. The milling was continued up to 30 h followed by isothermal annealing over a four interval of temperature from 350 to 650 °C held for 1 h. Crystallite size, lattice strain, lattice parameter were determined by Rietveld refinement structure analysis of X-ray diffraction data. The amount of dissolved/precipitated Mn (wt%) after ball milling/milling followed by annealing was calculated by quantative phase analysis (QPA). The increase of coercivity could be attributed to the introduction of lattice strain and reduction of crystallite size as a function of milling time. Electron paramagnetic resonance and superconducting quantum interface device analysis indicate that soft ferromagnetic behavior has been achieved by ball milled and annealed Cu–Mn alloy. The maximum coercivity value of Cu–Mn alloy obtained after annealing at 350 °C for 1 h is 277 Oe.