Glass formation and crystallization of Cu47Ti33Zr11Ni8X1 (X = Fe, Si, Sn, Pb) alloys

A group of Cu47Ti33Zr11Ni8X1 (X = Fe, Si, Sn, Pb, numbers indicate at.%) bulk glassy alloys was produced by copper mold casting. The glass-forming ability (GFA) and the devitrification behavior were investigated by differential scanning calorimetry and synchrotron experiments. The GFA was evaluated by considering different parameters: the reduced glass transition temperature Trg = Tg/Tl (Tl = liquidus temperature), the supercooled liquid region ΔTx = Tx − Tg and a new parameter γ defined as Tx/(Tg + Tl). s a maximum value of 57 K for Cu47Ti33Zr11Ni8Si1. Trg and γ reach the highest values for the Cu47Ti33Zr11Ni8Fe1 and Cu47Ti33Zr11Ni8Si1 alloys. The comparison of the parameters indicates that Trg and γ correlate better with GFA than ΔTx. In situ recorded XRD scans reveal that the first crystallizing phase has a γ-CuTi-type structure. The microstructure stable before melting contains a mixture of γ-CuTi, Cu51Zr14, Cu2TiZr and Ti2Cu compounds.