EXPERIMENTAL-DETERMINATION OF A TIME-TEMPERATURE-TRANSFORMATION DIAGRAM OF THE UNDERCOOLED ZR41.2TI13.8CU12.5NI10.0BE22.5 ALLOY USING THE CONTAINERLESS ELECTROSTATIC LEVITATION PROCESSING TECHNIQUE

High temperature high vacuum electrostatic levitation was used to dete rmine the complete time-temperature-transformation (TTT) diagram of th e Zr41.2Ti13.8CU12.5Ni10.0Be22.5 bulk metallic glass forming alloy in the undercooled liquid state. This is the first report of experimental data on the crystallization kinetics of a metallic system covering th e entire temperature range of the undercooled melt down to the glass t ransition temperature. The measured TTT diagram exhibits the expected ''C'' shape. Existing models that assume polymorphic crystallization c annot satisfactorily explain the experimentally obtained TTT diagram. This originates from the complex crystallization mechanisms that occur in this bulk glass-forming system, involving large composition fluctu ations prior to crystallization as well as phase separation in the und ercooled liquid state below 800 K. (C) 1996 American Institute of Phys ics.