UNDERCOOLING STUDIES OF THE BULK METALLIC GLASS FORMING Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10.0) Be_(22.5) ALLOY DURING CONTAINERLESS ELECTROSTATIC LEVITATION PROCESSING

摘要

Containerless processing was applied toinvestigate the thermal treatments affecting undercooling andvitrification of the bulk glass formingZr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10.0) Be_(22.5) alloy. Theexperiments were performed using the high temperature highvacuum electrostatic levitator at the Jet Propulsion Laboratory.A sample with a diameter of approximately 3 mm was melted,superheated, undercooled, and solidified while levitated underhigh vacuum. The results show that when the sample was heldabove its melting temperature for a sufficient period of time todissolve oxides and then cooled faster than a critical cooling rate,it undercooled to the glass transition temperature, Tg, andformed a glassy alloy. The required critical cooling rate formetallic glass formation was obtained to be between 0.9 K/s and 1.2 K/s.