Glass forming ability and crystallization behavior in amorphous Ti₅₀Cu_32-xNi₁₅Sn₃Be_x (x = 0, 1, 3, 7) alloys

The thermal stability and crystallization behavior of melt spun Ti₅₀Cu_32-xNi₁₅Sn₃Be_x (x = 0, 1, 3, 7) amorphous alloys were investigated by differential scanning calorimetry (DSC), X-ray diffractometry(XRD) and transmission electron microscopy (TEM). With increasing Be content, x from 0 to 7, ΔT_x gradually decreased from 73 to 45 K, but T_rg increased from 0.53 to 0.57. With increasing Be content, crystallization behavior changes from two exothermic events (x = 0, 1) to three exothermic events (x = 3, 7). Amorphous Ti₅₀Cu₃₂Ni₁₅Sn₃ phase crystallizes by transforming into Ti(Ni,Cu) and Ti₂Ni phases, followed by transformation into a mixture of Ti(Ni,Cu), TiCu, and Ti₃Sn phases. Amorphous Ti₅₀Cu₂₅Ni₁₅Sn₃Be₇ phase crystallizes by precipitation of a few nanometer scale crystalline phase followed by decomposition into a mixture of Ti(Ni,Cu), TiCu, Ti₃Sn and TiBe₁₂ phases at high temperature. Partial replacement of Cu by Be in Ti-Cu-Ni-Sn alloy improved the glass forming ability. A fully amorphous rod of the Ti₅₀Cu₂₅Ni₁₅Sn₃Be₇ alloy with a diameter of 2 mm was fabricated by injection casting.