Glass-to-glass transition enables superhigh thermal stability and glass formability for thermoplastic shaping of FeBNbYCr alloys

Fe-based bulk metallic glasses (BMGs) exhibit attractive properties, yet their thermal stability and glass formability (GFA) are always lower than the other thermoplastic shaping (TPS) alloys. Here, we developed a new Cr-doped Fe₆₅B_22.8Nb_3.7Y_4.5Cr₄ alloy with a super-wide supercooled liquid region (SCLR) (ΔT_x=112 K) and high GFA (≥ 3 mm) with industrial materials. Glassy rods can maintain the glassy structure after annealing and hot pressing at 923 K, and exhibit a high fracture strength of > 3000 MPa and hardness of > 900 H_v in annealed states. The BMG rods can be conveniently TPS in the SCLR with low compressive stress of < 250 MPa. It is found that the additional glass-to-glass transition (GGT) in the SCLR effectively improves the GFA and thermal stability, by complicating and postponing the transition and crystallization process. The introduction of GGT offers a new strategy to develop high-performance BMGs for precision TPS.