Microstructure and Magnetic Properties of FeCoZr(Mo)BGe Nanocrystalline Alloys

The microstructure and magnetic properties of Fe 40 Co 40 Zr 9 B 10 Ge 1 (Mo-free) and Fe 40 Co 40 Zr 5 Mo 4 B 10 Ge 1 (Mo-containing) nanocrystalline alloys, prepared using an amorphous crystallization method, were investigated. Mo addition affects the crystallization of the Fe 40 Co 40 Zr 9 B 10 Ge 1 amorphous alloy and decreases the grain size of the α -Fe(Co) phase below 650 °C. For the Mo-free alloy annealed at 600 °C and the Mo-containing alloy annealed at 575 °C, with a single α -Fe(Co) crystallization phase and approximately similar crystallization volume fractions, the Mo-containing alloy showed smaller, more regularly shaped grains and a significantly narrower grain-size distribution than the Mo-free alloy. The Fe and Co contents in the nanograins of the two alloys also differed. For the Mo-free alloy, a higher concentration of Co distributed in the residual amorphous matrix. For the Mo-containing alloy, a higher concentration Co dissolved in the nanograins. The specific saturation magnetization and coercivity of the Mo-free alloy were 1.05- and 1.59-times higher than those of the Mo-containing alloy, respectively.