Synthesis of bulk metallic glass in the Ti-rich part of the Ti-Cu-Ni-Sn-Be-Zr alloy system

Abstract

The glass forming ability and crystallization behaviour of melt Spun Ti50-xCU25Ni15Sn3Be7Zrx (x = 0, 3 and 5) amorphous alloys were investigated using differential scanning calorimetry (DSC), X-ray diffractometry and transmission electron microscopy. With increasing Zr contents, x from 0 to 5, ? T-x(= T-x - T-g) and T-rg(= T-g / T-l), where T-g=glass transition temperature, T-x=crystallization temperature and T-l=liquidus temperature, gradually increase from 45 K to 56 K and from 0.57 to 0.60, respectively The Ti50Cu25Ni15Sn3Be7 alloy shows three exothermic events in the DSC curve; initially the alloy crystallizes by forming a few nanometer scale crystalline phase, followed by decomposition into a mixture of Ti(Ni,Cu), TiCu, Ti3Sn, and TiBe12 phases at high temperature. Furthermore, the alloys containing Zr exhibit the formation of nanocrystalline phases of similar to10 nm size even after the second exothermic event due to their increased atomic packing density. For the Ti45Cu25Ni15Sn3Be7Zr5 alloy, fully amorphous rods up to 5 mm in diameter were successfully fabricated by injection casting.