Microstructural evolution of laser-welded Ti-based bulk metallic glass

Abstract

A fiber laser beam is used to butt-weld of identical Ti43·3Zr21·7Ni7·5Be27.5 (at.%) bulk metallic glass (BMG) specimens. Various tests, such as SEM, TEM, XRD, DSC, and Vickers hardness, are conducted on the welded specimens to analyze the crystalline phases generated at the HAZ of each specimen during welding. The heat-affected zone (HAZ) can be obviously identified in the welded specimens owing to the clustering of the crystalline phases. The HAZ is composed of a heterogeneous group of crystalline phases, such as Ti–Zr–Ni polygonal phase, Ti and Ti–Zr dendritic phase. These crystalline phases decrease the glass transition temperature (Tg) of the welding fusion zone (WFZ) and increase the hardness at the HAZ.

Keywords

• Bulk metallic glass (BMG)
• Laser welding
• Phase evolution
• Crystalline