Unique influence of heating rate on the magnetic softness of Fe81.5Si0.5B4.5P11Cu0.5C2 nanocrystalline alloy

Abstract

• A finely uniform nano-crystalline structure with α-Fe phase can be obtained after slow annealing. • Small α-Fe crystals precipitated from amorphous matrix by annealing contributes to a low coercivity of 4.8 A/m. • The nano-crystallized mechanism during slow-heating-annealing process is unusual and different with NANOMET. • The simplification of the crystallization process in industry by a one-step annealing. Fe 81.5 Si 0.5 B 4.5 P 11 Cu 0.5 C 2 nanocrystalline alloy with high Fe concentration possesses a finely uniform nanocrystalline structure and numerous α-Fe crystals with a mean grain size of ∼17 nm based on XRD patterns. Such crystals precipitated from the amorphous matrix. Favorable soft magnetic properties, small value of coercivity ( H c ) of ∼4.8 A/m, and high magnetic flux density ( B s ) of ∼1.53 T can be achieved by slow heat treatment (heating rate of ∼10 °C/min). In this case, one-step annealing at a low heating rate is truly antipodal to Fe–Si–B–P–Cu alloy. We analyzed the nanocrystallized mechanism during annealing with various heating rates in Fe 81.5 Si 0.5 B 4.5 P 11 Cu 0.5 C 2 alloy, which inevitably simplified the industrial crystallization process by one-step annealing at a low heating rate.