Experiment and simulation of hot embossing of a bulk metallic glass with low pressure and temperature

Abstract

The thermoplastic forming process of a bulk metallic glass (BMG) is simulated using commercial software DEFORM 3D and verified by hot-embossing experiment in this study. The fabrication process of micro-electro-mechanical systems (MEMS) includes a photoresist reflow technique, and Nickle–Cobalt (Ni–Co) electroplating to fabricate a first mold. Then, this mold is applied to hot emboss on an Mg–Cu–Y amorphous alloy to form a secondary mold. The thermal properties of the BMG material such as the glass transition temperature (Tg) and the onset temperature (Tonset) for the viscous flow are investigated using a differential scanning calorimetry (DSC) and a thermomechanical analyzer (TMA). The Tg of BMG is around 413 K (140 °C). The hot-embossing temperature is set at 423 K (150 °C). The supercooled liquid region ΔT between the Tg and the crystallization temperature (Tx) is the working temperature for the microforming study. This embossing process shows that the thermoplastic forming ability of the BMG material is better than polymethylmethacrylate (PMMA) which requires high hot-embossing pressure and temperature. BMG is not only a good material for the hot-embossing process to fabricate micro-structure directly, but also a fast-forming material for mold (or die) fabrication.