Micro-shaping of metallic glass by wire electrochemical micro-machining with a reciprocating traveling workpiece

Abstract

Metallic glasses exhibit many outstanding properties, such as high hardness and strength, but their micro-shaping is still challenging. The technique of wire electrochemical micro-machining (WECMM) with a reciprocating traveling workpiece is proposed firstly for complex micro-shaping of metallic glasses. WECMM has increasingly become recognized as a versatile technique for producing planar contour micro-features, and holds promise for the micro-shaping of metallic glass structures. In WECMM, the processing performance is significantly affected by the mass transport rate in the narrow inter-electrode gap. Therefore, a new method with a reciprocating traveling workpiece is developed to enhance mass transport. Analysis of the electric field and flow field indicates that the reciprocating motion of the workpiece can facilitate active removal of electrolysis products and rapid refreshment of electrolyte, both of which are beneficial for maintaining a stable current density distribution on the machining surface. Taking a Ni-based metallic glass, Ni72Cr19Si7B2, as an example, the polarization and processing characteristics in dilute acid electrolyte are investigated. An overall improvement in processing performances is achieved. Finally, several complex five-layered microstructures are fabricated successfully using the optimized parameters. The resulting surface roughnesses Ra and Rmax are just 0.018 μm and 0.225 μm, respectively. The total machining efficiency in terms of feed rate reaches 4.0 μm/s.