Optimization of Holographic Imprinting Process for Metallic Glass using Thermoplastic Forming

Abstract

The thermoplastic forming (TPF) process of metallic glass (MG) is a unique and powerful method that cannot be performed using conventional crystalline alloys. Because the mechanical and thermal properties of MGs are more favorable with smaller sample sizes, TPF is particularly useful for microscale and nanoscale part molding and micro-patterning. One of the promising commercial MG applications that can take full advantage of these characteristics is hologram patterning. Holograms can be used to identify unique brands, using characteristics with patterns that are difficult to replicate. Their excellent aesthetic qualities can also greatly contribute to increased product value. In this study, we developed and performed a TPF process for actual holographic imprinting with Mg-based MGs, and further investigated the TPF processing window, covering a wide range of temperature and process time conditions through thermal analysis, with ultra-fast heating rates ranging from 100 to 25000 K/s using Flash-DSC. The results of this study serve as a practical guide for identifying the full range of TPF processing windows including conventional and ultrafast heating conditions for micro-scale and nanoscale molding of various MGs. Moreover, a methodology is proposed to identify the general TPF processing window (<i>η</i><10<sup>8</sup>Pa· s) and the ideal TPF processing window (<i>η</i><10<sup>4</sup>Pa· s) by estimating the viscosity (<i>η</i>) of the supercooled liquid. Accordingly, this study is expected to be utilized to optimize the TPF process of MGs and promote the commercialization of related industries.