Rheometry and Crystallization of Bulk Metallic Glass Forming Alloys at High Temperatures

Melts of the Zr 41.2 Ti 13.8 Cu 12.5 Ni 10.0 Be 22.5 bulk metallic glass forming alloy contained in high purity graphite crucibles have been supercooled allowing for the measurement of thermodynamic and rheological properties of the equilibrium and supercooled liquid. Strong resistance to heterogeneous nucleation is found and amorphous samples can be formed with critical cooling rates of less than 2 K/s, comparable to results found from levitation experiments. Complementary experiments under isothermal conditions and linear continuous cooling cannot be described by an effective steady state nucleation rate in the framework of classical nucleation theory.