Micro viscous flow processing of Fe-based metallic glassy particles

Abstract

Fe-based metallic glasses are difficult to plastically form into complex shapes in their supercooled liquid region because of their rather high viscosity and low thermal stability. In this study, we proposed a novel two-step fabrication process for micro components using viscous flow of an Fe-based metallic glass. First, we prepare mono-sized [(Fe0.5Co0.5)0.75 Si0.05B0.2]96Nb4 spherical particles with precisely controlled volumes that correspond to the desired micro component volume. It is essential that the prepared spherical particles be composed of a single glassy phase. Then, one prepared particle is die-pressed into one micro component under the supercooled liquid region. The main deformation mechanism is viscous flow and the micro hot-press apparatus was used to realize the optimal processing conditions for micro viscous flow. The processed micro gear maintained the fully glassy phase, resulting in excellent mechanical strength, up to 1125 HV on average by the Vicker hardness test. Crystallization of the material during processing has been discussed related to the process temperature and deformation rate using the model of Kaysser and Arzt.