Metallic Glacial Glass Formation by a First-Order Liquid-Liquid Transition

The glacial phase, with an apparently glassy structure, can be formed by a first-order transition in some molecular-glass-forming supercooled liquids. Here we report the formation of metallic glacial glass (MGG) from the precursor of a rare-earth-element-based metallic glass via the first-order phase transition in its supercooled liquid. The excellent glass-forming ability of the precursor ensures the MGG to be successfully fabricated into bulk samples (with a minimal critical diameter exceeding 3 mm). Distinct enthalpy, structure, and property changes are detected between MGG and metallic glass, and the reversed "melting-like" transition from the glacial phase to the supercooled liquid is observed in fast differential scanning calorimetry. The kinetics of MGG formation is reflected by a continuous heating transformation diagram, with the phase transition pathways measured at different heating rates taken into account. The finding supports the scenario of liquid-liquid transition in metallic-glass-forming liquids.