Centimeter-sized Ti-rich bulk metallic glasses with superior specific strength and corrosion resistance

Since increasing Ti content in Ti-based metallic glasses would benefit their specific strength, developing Ti-based bulk metallic glasses (BMGs) with high Ti content has drawn great attention of researchers. However, excessive Ti content usually deteriorates their glass forming ability (GFA), especially for Ti-based BMGs with Ti content higher than 50 at.%. Here, based on the Ti ₅₅ Zr ₁₅ Be ₂₀ Ni ₁₀ BMG with a critical diameter of 5 mm, the (Ti ₅₅ Zr ₁₅ Be ₂₀ Ni ₁₀ ) _100-x Fe _x alloys were designed and investigated. The (Ti ₅₅ Zr ₁₅ Be ₂₀ Ni ₁₀ ) ₉₆ Fe ₄ BMG exhibited a critical diameter of 10 mm, suggesting GFA of the Ti ₅₅ Zr ₁₅ Be ₂₀ Ni ₁₀ BMG could be improved by Fe addition. In addition, their yield strength increased with Fe addition, thus the specific strength was enhanced from 3.98 × 10 ⁵ N m/kg to 4.46 × 10 ⁵ N m/kg, providing the most optimal scheme of specific strength and GFA among the reported Ti-based BMGs. The developed BMGs exhibited high pitting potentials in 3.5 wt.% NaCl aqueous solution, which were 1.8~2.8 times higher than that of 304 stainless steel. The present result shows that the developed Ti-based BMGs containing high Ti content, combined with high specific strength, large glass forming ability and good corrosion resistance, are promising for applications requring lightweight alloys.