Magnetic properties and a structure model for high Fecontent Fe–B–Si–Zr bulk glassy alloys

• High Fe-content Fe-B-Si-Zr metallic glasses are designed with a cluster-plus-glue-atom model.
• Bulk glassy rods with diameters 1–2.5 mm are reached at the [Si-B2Fe7.6Zr0.4]Fe + Fex model compositions.
• These glassy alloys exhibit high Bs (1.29–1.54 T) and low Hc (0.5–1.7 A/m).
• Structure and properties correlation is discussed using the double cluster model.

The present study is devoted to developing high Fe-content Fe-B-Si-Zr bulk metallic glasses (BMGs) with good soft magnetic properties and exploring their structure-property correlations. Using the atomic-cluster-plus-glue-atom model, a series of high Fe-content Fe-B-Si-Zr quaternary alloys, namely [Si-B2Fe7.6Zr0.4]Fe + Fex (x = 0, 0.5, 1, 1.5, 2, 2.5 and 3), have been derived from a basic BMG composition formula of [Si-B2Fe7.6Zr0.4]Fe (Fe71.7B16.7Si8.3Zr3.3). Our experimental results show that the critical glass formation size gradually decreases from 2.5 mm to 1 mm with increasing Fe-content. [Si–B2Fe7.6Zr0.4]Fe + Fe2.5 (Fe76.5B13.8Si6.9Zr2.8) glassy alloys exhibit high saturation magnetization of Bs ~ 1.54 T and a very low coercive force of Hc ~ 0.5 A/m. The deceasing tendencies of the glass transition temperature, thermal stability, glass-forming ability and Curie temperature with increasing Fe-content in the series of alloys are discussed in view of the occurrence of micro-segregation of Fe clusters in the model structure.