Bending ductility of stress-relieved Fe–Zr–B metallic glasses with pronounced β-relaxation

Fe-based metallic glasses are known to have excellent soft magnetic properties, but restricted to the disastrous annealing embrittlement. A novel class of Fe84-xB14+x Zr2 (x = 0, 3, 6) metallic glasses with extraordinary annealing bending ductility and excellent soft magnetic properties were developed. The metallic glasses exhibit a high BS of 1.54–1.64 T and a low HC of 4.1–5.8 A/m. It is noteworthy that the Fe84B14Zr2 metallic glass exhibits the highest ductile to brittle transition temperature among all Fe-based metallic glasses reported to date and the ductile to brittle transition temperature decreases with the decrease of Fe content. Moreover, the well-distributed shear bands can still be formed during bending for Fe84B14Zr2 metallic glass after 680 K annealing. Pronounced β-relaxation peak has been observed for Fe84B14Zr2 metallic glass in its relaxation spectra. We demonstrate that the bending deformation ability is closely correlated to the β-relaxation. The underlying mechanism for the extraordinary bending deformation ability of Fe84B14Zr2 metallic glass after annealing can be attributed to the heterogeneous structure with plenty of loosely packed zones as revealed by the pronounced β-relaxation and high resolution transmission electron microscopy. •Fe84B14Zr2 MG with good soft magnetic properties exhibits extraordinarily high DBT temperature.•Fe84B14Zr2 MG shows pronounced β-relaxation, relating to plenty of loosely packed zones.•The β-relaxation is regarded as an indication for the bending ability of metallic glasses after annealing.