Role of Mo addition on structure and magnetic properties of the Fe85Si2B8P4Cu1 nanocrystalline alloy

The amorphous-forming ability (AFA), crystallization structure and magnetic properties of the melt-spun Fe-85 - xSi2B8P4Cu1Mox (x = 0-2) alloys were investigated. The addition of 1-2 at% Mo in the Fe85Si2B8P4Cu1 alloy enhances the AFA with increasing the critical thickness for amorphous formation from similar to 14 to similar to 20 mu m. The Mo alloying refines the microstructure and reduces the coercivity of the annealed alloys, and weakens the dependence of the coercivity on the heating rate, although it decreases the saturation magnetic flux density. After annealing under a low heating rate of 50 K/min, the average alpha-Fe grain size and coercivity of the Fe84Si2B8P4Cu1Mo1 alloy are similar to 25 nm and 23.9 A/m, respectively, which are lower than those of similar to 32 nm and 40.5 A/m for the base alloy. In addition, the mechanism related to the effects of Mo on the structure and magnetic properties was discussed in term of the crystallization activation energy.