Fe-Mn-Cr-Mo-(Y,Ln)-C-B (Ln = lanthanides) bulk metallic glasses as formable amorphous steel alloys

The glass formability of high-manganese amorphous steel alloys reported earlier by us has been found to improve upon additions of yttrium and lanthanide elements, enabling the formation of bulk glassy samples with diameter thicknesses reaching 7 mm by casting. Based on extensive studies using different Ln additions and systematic measurements of alloy oxygen contents, the intrinsic roles of Y/Ln in attaining good glass formability in both the high-Mn alloys and previously reported high-Cr alloys are revealed. The yield strengths of the non-ferromagnetic glassy alloys obtained are estimated to be three times those of high-strength stainless steel alloys, and high elastic moduli in the range 150-200 GPa are measured. Furthermore, in the supercooled liquid regions, the glassy rods can be bent into various configurations by hand without fracturing. The observed plastic behavior together with the measured high mechanical strengths suggests that the present Fe-based bulk metallic glasses can potentially be developed as formable non-ferromagnetic amorphous steel alloys.