Analysis of groove quality and machining behavior of Zr-based metallic glass through laser grooving and electro-jet machining

Abstract

Conventional machining of metallic glass is a challenge due to its amorphous nature and inherent brittleness. This work investigates the non-conventional machining of Zr-based metallic glass, Vitreloy-1, using laser processing with a Yb-fiber laser and an electro-jet milling (EJM) process. Grooves were fabricated using these techniques in Vitreloy disks of 1.5 mm thickness to study the machining behavior. The grooves formed with the laser were smooth, although there was observation of dross at the groove edges, which was selectively removed through the EJM process. On the other hand, the EJM process was found to produce dross-free grooves; however, it caused leaching of zirconium from the groove zone, which was understood from the elemental maps obtained using the scanning electron microscope. A comparison of the laser grooving and EJM grooving process was also carried out using Vickers micro-indentation. Indentations made close to the groove edge in laser grooved samples developed shear bands but the same were absent in the EJM grooved samples. Since shear banding tendency is an indicator of the inherent toughness of the metallic glass, the laser grooving technique is found more suitable for nonconventional machining of metallic glass.

Multi-Scale Traditional and Non-Traditional Machining of Bulk Metallic Glasses (BMGs)—Review of Challenges, Recent Advances, and Future Directions

“…The crater shows clear ripple formation at the edge of the crater, while providing very smooth surface in the middle. [128] used a Yb-fiber laser and electro-jet milling (EJM) processes to machine grooves on the Zr-based BMG. It was reported that EJM process reduced or minimized the dross at the groove edges, which was comparatively more visible for laser machining of BMG.…”

“…SEM image of (a) a crater formed and (b) ripple formation at the crater boundary using the laser energy of 0.053J and lens-to-sample distance of 150 mm (focal length of the lens) [127]. (Copyright: Authors, ASME).Melkani et al (2022)[128] used a Yb-fiber laser and electro-jet milling (EJM) processes to machine grooves on the Zr-based BMG. It was reported that EJM process reduced or minimized the dross at the groove edges, which was comparatively more visible for laser…”

Electrochemical jet manufacturing technology: From fundamentals to application

“…For example, EMM studies on Zr-based metallic glasses indicate poor process response towards NaNO3 electrolytes [190]. Melkani et al [191] used an EJM process with NaCl electrolyte to remove dross from the walls of laser machined Zr metallic glass, although the authors reported leaching of Zr from the top surface.…”

Fabrication of Dimples by Jet-ECM of Zr-Based Bulk Metallic Glasses with NaCl-Ethylene Glycol Electrolyte

“…During the process, the electrolyte is ejected from the cathode nozzle in a positive flow manner, and an electrical potential is applied between the workpiece and the nozzle. The high-flow-rate electrolyte can remove the scum produced by processing, and there is no concomitant effect on the processing surface [17]. Many researchers have already used this technology to create various microstructures, such as dimples and channels, which have been applied in aerospace, medical devices, biomedical applications and microelectronics.…”