Micropatterning of Ni-based metallic glass by pulsed wire electrochemical micro machining

Abstract

The technique of wire electrochemical micro machining (WECMM) is proposed firstly for the micropatterning of Ni-based metallic glass in this paper. Metallic glass (MG) exhibits many outstanding properties such as high hardness and strength, which enable it to be used as functional and structural materials in micro electromechanical systems (MEMS). A significant limitation to the application of MGs is the challenge of shaping them on micro scale. WECMM is a non-traditional machining technique to fabricate microstructures that has some unique advantages over other methods, which will be a promising technique for micro shaping of metallic glass structures. Taking the example of a Ni-based glassy alloy, Ni72Cr19Si7B2, the polarization and fabrication characteristic in dilute hydrochloric acid electrolyte were investigated. Changes in the machined slit width in terms of several experimental parameters were investigated to find the optimal ones. Finally, the optimal machining parameters: HCl electrolyte concentration of 0.1 M, applied voltage of 4.5 V, pulse duration of 80 ns, pulse period of 3 μs and feed rate of 0.3 μm s−1 were employed for the fabrication of microstructures. Such as a micro square helix with a slit width of 14.0 μm, standard deviation of 0.2 μm and total length up to 2000 μm, along with a micro pentagram structure with side length of 90 μm and sharp corner of 36°, were machined with a high level of stability and accuracy.