Thermo-mechanical coupled flow behavior evolution of Zr-based bulk metallic glass

Abstract

Machining is an essential process for manufacturing high-precision bulk metallic glass (BMG) components, but the flow behavior of thermodynamically metastable BMGs during machining with high temperature and high strain rate conditions is still unclear. In this study, the flow behavior of Zr-based BMG is investigated in an orthogonal cutting operation. The results show that the increase of the temperature at the initial stage of cutting enables the amorphous chips gradually change from a laminated structure to a viscous flow state, and attach to the cutting edge of the tool. The chip in the stable sticking area of the tool-chip interface is a composite material rich in various crystalline phases and quasi-crystals with obvious phase separation, while the chips far away from the interface still maintain the amorphous state with uniform composition. After the formation of stable adhesion, the cutting force and cutting temperature are relatively stable, and the viscous-fluid chips act as a protective layer for the tool, avoiding severe tool wear.