Thermal behavior, microstructure and magnetic properties of (FexNiyCoz)80B10Si2Cu1Zr7 alloys

Abstract

Amorphous (FexNiyCoz)80B10Si2Cu1Zr7 (x + y + z = 1) alloys were prepared by melt spinning. By investigating the glass-forming ability, thermal behavior, crystallization and magnetic properties of alloy ribbons, detailed and integral pseudoternary diagrams of (FexNiyCoz)80B10Si2Cu1Zr7 alloys were constructed, which can make one clearly understand the effects of ferromagnetic elements (Fe, Co, Ni) on microstructure and physical properties. Results show that, all as-spun alloys show a fully amorphous structure and the coercivity (Hc) can be tuned to a lower value than 45 A/m. After being annealed, alloys with Ni content lower than 64 at.% (y < 0.8) show a refined structure of nanocrystals with an average size about 3–14 nm uniformly dispersed in the residual amorphous matrix, and the Fe-rich and Ni-rich alloys exhibit Hc < 155 A/m comparing with the Co-rich alloys (155–416 A/m). No matter as-spun or annealed alloys, (Co + Ni):Fe = 3:7 is the optimal composition to obtain the maximum saturation magnetization (Ms) when y is a certain value in the range of 0–0.2. In addition, alloys in the whole range of composition were classified according to comprehensive magnetic properties of Ms and Hc. The Fe-rich alloys exhibit typical soft magnetic characteristics of simultaneously high Ms and low Hc, as well as high thermal stability of fully amorphous structure or uniform “primary crystalline phase + residual amorphous” structure. All results give a better insight for amorphous and nanocrystalline (FexNiyCoz)80B10Si2Cu1Zr7 alloys to further analyze more efficient magnetic alloys in inductors, transformers, magnetic recording and other magnetic functional materials.