Microstructure and magnetic properties of FeCoZr(Mo)BGe nanocrystalline alloys

The microstructure and magnetic properties of Fe40Co40Zr9B10Ge1（Mo-free） and Fe40Co40Zr5Mo4B10Ge1（Mocontaining） nanocrystalline alloys,prepared using an amorphous crystallization method,were investigated.Mo addition affects the crystallization of the Fe40Co40Zr9B10Ge1 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 singleα-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.