Solidification Analyses for the Fabrication of Bulky Multicomponent Metallic Glasses and their Properties

<jats:title>Abstract</jats:title><jats:p>The liquid-crystalline transformation during continuous cooling was examined for a Zr<jats:sub>60</jats:sub>Al<jats:sub>10</jats:sub>Ni<jats:sub>10</jats:sub>Cu<jats:sub>15</jats:sub>Pd<jats:sub>5</jats:sub> alloy which was ejected into a wedge-shape cavity in a copper mold or solidified on a copper hearth by unidirectional arc melting. The structure consists of a glassy phase in the wedge angles smaller than 10 degrees and changes to glassy and crystalline phases in the higher angle range. The start (Cs) and termination (Ct) points for the transformation were determined and the continuous-cooling-transformation (C. C. T. ) curves were constructed. The nose temperature (Tn) and the time (tn) up to the nose point in the C. C. T. curves were 1018 K and 0.93 s. The critical cooling rate for glass formation defined by (Tm-Tn)/tn is 110 K/s. Furthermore, with the aim of clarifying a solidification condition for formation of a bulk glassy alloy by unidirectional arc melting, the relation between the formation of a glassy phase and the solidification parameters of moving velocity of liquid/solid interface (V), temperature gradient (G) and cooling rale (R) was examined. The glassy phase was obtained in the condition of V>3 mm/s, G>4 K/mm and R>40 K/s. The supercooling reaches 385 K at 40 K/s. The large supercooling ability is presumably due to the formation of a highly dense randomly packed structure where the nucleation of a crystalline phase and the atomic rearrangement for growth reaction are difficult.</jats:p>