Glass Forming Ability and Crystallization Behavior in Amorphous Ti<SUB>50</SUB>Cu<SUB>32-x</SUB>Ni<SUB>15</SUB>Sn<SUB>3</SUB>Be<SUB>x</SUB> (x=0, 1, 3, 7) Alloys

Abstract

The thermal stability and crystallization behavior of melt spun Ti50Cu32−xNi15Sn3Bex (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, ΔTx gradually decreased from 73 to 45 K, but Trg 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.