Thermodynamic assessment of Fe-B-P-Cu nanocrystalline soft magnetic alloys for their crystallizations from amorphous phase

Abstract

The crystallization processes of Fe83.3+xB7-xP9Cu0.7 (x = 0 to 2.5 at%) amorphous alloys were thermodynamically assessed using Thermo- Calc software with TCFE7 database for Fe-based alloys. The analysis of the alloys for a primary crystallization precipitating bcc-Fe revealed metastability among four phases comprising bcc-Fe, two kinds of Fe-based amorphous phases that are rich in Fe-B and Fe-P and crystalline Curich phase. The roles of P and Cu additions to the Fe-based amorphous alloys are thermodynamically interpreted as stabilizing the remaining amorphous phase at the primary crystallization. The dual Fe-rich amorphous phases due to the inclusion of P characterize a heterogeneous amorphous structure of NANOMET family alloys comprising Fe and metalloids mainly and without early-transition metals.