A Ti–Zr–Be–Fe–Cu bulk metallic glass with superior glass-forming ability and high specific strength

It has been found that alloying with Cu element could significantly enhance the glass-forming ability (GFA) of Ti–Zr–Be–Fe alloy. As a result, a series of centimeter-scale (Ti ₄₁Zr ₂₅Be ₂₈Fe ₆) _100−xCu _x ( x = 0–20 at.%) bulk metallic glasses (BMGs) have been developed. Especially for those with x = 7–13 at.% Cu content, the critical size is larger than 20 mm. Among these Ti-based BMGs, (Ti ₄₁Zr ₂₅Be ₂₈Fe ₆) ₉₁Cu ₉ (also noted as Ti _37.31Zr _22.75Be _25.48Fe _5.46Cu ₉ ) glassy alloy exhibits superior GFA with a critical size larger than 32 mm, which is the largest size of Ti-based BMGs ever reported so far. The enhancement of the GFA is suggested to arise from the Cu addition-induced decrease in both the liquidus temperature and the Gibbs energy difference between the undercooled liquid and the crystalline phases of Ti–Zr–Be–Fe alloy. In addition to its superior GFA, the lightweight (Ti ₄₁Zr ₂₅Be ₂₈Fe ₆) ₉₁Cu ₉ alloy also exhibits a remarkable high specific strength of 3.7 × 10 ⁵ N m kg ⁻¹ and an apparent plastic strain of 1.2%.