Filling kinetics of Zr-based amorphous supercooled liquid in micro filling process with longer unsteady flow

The hot-embossing tests of Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 (Vit1) bulk metallic glass (BMG) have been performed under various experimental parameters. The filling features of prepared micro channels, such as filling height, aspect ratio and surface quality, were observed by scanning electron microscope and laser scanning confocal microscopy. It is suggested that the velocity gradient induced by friction force produces an arc-shaped flow front on the BMG micro channel. The filling heights of micro channels increase with increasing processing temperature, embossing pressure and cavity width. The aspect ratio decreases sharply on increasing the cavity width from 20 μm to 50 μm and remains approximate constant when the cavity width exceeds 200 μm. Considering the BMG supercooled liquid should not be within steady flow state at the early stage of the hot-embossing experiment, which is inconsistent with the common assumption of Hagen-Poiseuille equation, an universal equation has been developed by introducing the contribution of linear loading process to filling behavior. Comparison results prove that the theoretical calculations are in better agreement with the hot-embossing test data, thus verifying the validity and accuracy of the new kinetic equation.