Fragility and thermal stability of Pt- and Pd-based bulk glass forming liquids and their correlation with deformability

The fragility parameter m of (Pt or Pd)–(Ni, Cu)–P bulk metallic glasses (BMGs) was characterized and compared to other systems. The results indicate that the Pt65Ni15P25 alloy is the most fragile and thermally stable at the supercooled liquid state, thus is the most workable among the presently developed BMGs. To express the degree of workability, a deformability d∗=log[η(Tg∗)/η(Tx)] is introduced then correlated with m   and the reduced thermal stability ΔTrx∗=(Tx-Tg∗)/Tg∗. A master curve in term of η(Tg∗)/η(T) and m·[(T-Tg∗)/Tg∗] has been established for various BMGs, d∗ thus can be uniquely related to m·ΔTrx∗.