Effect of rare earth additions on microstructure, thermal stability and crystallization behavior of melt spun Fe80.65Cu1.35Si2B14RE2 (RE=Y, Gd, Tb and Dy) soft magnetic alloys

• Addition of RE improve the amorphous forming ability of the alloys.
• Addition of RE significantly increase the thermal stability of the alloy.
• Addition of RE change the crystallization behavior of the as-spun alloys.
• A steady existence of metastable Fe3B phase during annealing in RE doped alloys.
• Addition of Y slightly reduces the Bs, while the Hc significantly decreases.

The influences of RE alloying additions (Y, Gd, Tb and Dy) on the microstructure, thermal stability and crystallization behavior of melt spun Fe80.65Cu1.35Si2B14RE2 alloys have been systematically investigated. Substituting 2 at% iron atoms by rare earth elements significantly improve the amorphous forming ability and thermal stability of the alloys. The primary crystallization temperatures are increased for at least 55 °C. The crystallization behavior is dramatically changed with a steady existence of metastable Fe3B phase in the second stage of crystallization during the annealing process. For Fe80.65Cu1.35Si2B14Gd2 alloy, the Fe3B phase can be stably exist even the temperature rise up to 600 °C. The addition of Y is found to be beneficial for the soft magnetic application of the alloy.