Structural and magnetic properties of nanocrystalline (Fe-Cu)93Zr7 alloys prepared by mechanical alloying

Nanocrystalline ferromagnetic (FexCu100 − x)93Zr7 alloys (x = 50, 70) were prepared by mechanical alloying of elemental powders. For x = 70 a supersaturated bcc solid solution forms upon milling, whereas a supersaturated fcc solid solution is observed for x = 50. The deformation during milling reduces the grain size of the alloys to about 5 nm. Heating to elevated temperatures leads to structural relaxation, phase separation and grain growth of the metastable solid solutions. Upon heating to 670–970 K the as-milled Fe-rich bcc phase decomposes into α-Fe and a Cu-rich solid solution, whereas the initially Cu-rich fcc solid solution transforms into a mixture of pure Cu and to pure α-Fe. The magnetic properties of as-milled and annealed powders will be discussed with respect to the composition and the microstructure of the material, the plastic deformation during milling and the strain release and decomposition upon subsequent heating.