Nontoxic, precious-metal-free titanium-based metallic glasses with exceptional glass-forming ability and high specific strength

Titanium-based metallic glasses (TBMGs) are attracting broad interest due to their simultaneous light weight, superhigh strength, and specific strength, exceptional wear- and corrosion-resistance and biocompatibility, desirable for electronic, biomedical, and aerospace applications. However, the glass-forming ability (GFA) of TBMGs, except some containing significant amount of toxic (Be) or precious (Pd, Ag) elements, is disappointingly low, as manifested by a critical casting diameter (dc) not more than 6 mm, which significantly restricts their manufacturing and applications. Here, we report our discovery of a series of TBMGs in the (TiZrHf)x(CuNi)y(SnSi)z pseudo-ternary system. These alloys possess an exceptionally large dc, reaching up to 12 mm, doubling the current record for Be and precious-metal free TBMGs. Moreover, these alloys exhibit a low density (7.0–7.3 g/cm3), high fracture-strength (up to ∼2700 MPa), high specific fracture-strength (up to ∼370 N m g−1), and even good plasticity with a plastic strain of up to 9.4% upon compression. They also possess high activation energy for crystallization and high atomic packing efficiency, which provide an initial physical account for their exceptional GFA and manufacturability.