Optimizing Surface Finish and Material Removal Rate in Wire EDM of Zirconium-Based Bulk Metallic Glass Vitreloy 1: A Parametric, Elemental, Recast Layer, and Hardness Analysis

Abstract

Wire electric discharge machining (WEDM) is a precision machining technique suitable for difficult-to-cut materials like bulk metallic glasses (BMGs). The extreme hardness and amorphous structure of BMGs make conventional machining challenging, necessitating careful control of machining parameters. This study investigates the effect of machine feed rate and duty factor on material removal rate (MRR), surface finish (Rₐ), and surface topography (Sₐ) of zirconium-based BMG Vitreloy 1 (Vit1) in WEDM, keeping other processing parameters as constant. Experimental results reveal that MRR increases with the increase in the machine feed rate, while surface finish and topography deteriorate with increasing machine feed rate and duty factor. Energy-dispersive X-ray spectroscopy (EDS) study on the surface images carried out in field emission scanning electron microscope has also been employed to evaluate the elemental characteristics of the machined surface by spectral imaging, point-and-shoot, line mapping, and EDS mapping technique. EDS study proves the migration of element zinc from electrode wire to machined surface. The study of the recast layer on the machined surface as well as on the surface along the cross section, perpendicular to the wire feed along the horizontal direction, reveals that the surfaces are porous with the presence of a flaky layer of debris and several pore holes, globules, and very fine cracks. The measurement of micro-hardness demonstrates the increase in the hardness of machined surface than parent Vit1 as electrical discharge converts Vit1 surface into a carbide surface. © King Fahd University of Petroleum & Minerals 2025.