Influence rules of early transition elements on rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content.

• The ETEs additions improve thermal stability of the rapid solidified alloys. • Adding ETEs inhibit the formation of α-Fe crystals during rapid solidification. • Slightly rises in δ and negative Δ H mix coarsen the crystals in annealed alloys. • Excessive high δ and negative Δ H mix refine the crystals on the contrary. • The variation in crystal size results from the combined action of rapidly decline in competitive growth and slowly enhancement in diffusion inhibition effect during nanocrystallization. Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability, and also results in unusual phenomena in terms of alloying effects. In the present work, we systematically studied the influence rules of early transition elements on the rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content and explored the related mechanisms. In terms of rapid solidified structure, the additions of early transition elements always inhibit the formation of pre-existing α-Fe crystals even eliminate them, and the additions that could produce larger atomic mismatch parameter (δ) and negative mixing enthalpy (Δ H mix) show stronger effects. In terms of nanocrystallization behaviors, the increases in δ and negative Δ H mix weaken the competitive growth between the pre-existing nanocrystals during annealing and then coarsen the nanostructure of the annealed alloys and deteriorate their magnetic softness, while the excessive increases in δ and negative Δ H mix could significantly suppress the growth of α-Fe crystals by diffusion inhibition during annealing and thus remarkable refine the nanostructure of the annealed alloys and improve their magnetic softness. [ABSTRACT FROM AUTHOR]