Electrochemical micromachining of a Zr-based bulk metallic glass using a micro-tool electrode technique

For the first time the possibility of electrochemical micromachining (ECMM) of a Zr-based bulk metallic glass (BMG) using a micro-tool electrode technique is reported. It is demonstrated that the choice of the electrolyte chemistry is substantial for a successful ECMM processing. For the bulk glassy Zr59Ti3Cu20Al10Ni8 alloy a concentrated aqueous NaNO3 standard machining solution is not suitable due to formation of thick and dense corrosion product layers which hinder the machining of structures with high aspect ratio. On the other hand, a commercial methanolic HClO4 solution is shown to be very promising. In the first experiments with this electrolyte micro-hole structures were machined with aspect ratios of about 1 at depths of ∼40 μm. The effect of process parameters such as pulse voltage and pulse length was investigated and their influence on the machined structure morphology is established. In a first approach the potential and challenges of this electrochemical micromachining technique for microforming of multi-component bulk metallic glass surfaces will be discussed.