Surface integrity investigation of a Zr52.5Ti5Cu17.9Ni14.6Al10 metallic glass after grinding

Crystalline alloys, widely used in the industry, are a topic of important research regarding their integrity resistance towards machining. Such investigations are less intense when dealing with relatively newer and less popular materials such as bulk metallic glasses (BMGs). This is even truer when specific machining techniques, such as grinding, are involved. As BMG are increasingly promoted to diverse industrial areas, the study of the impact of grinding on their microstructural integrity is necessary. Indeed, the amorphous structure of BMG, at the origin of their remarkable properties, is metastable such that any exterior solicitation (heating, cooling, loading, etc.) can induce structural modifications, for instance local crystallisation, and therefore degrade or at least modify their characteristics. Using quick and straightforward characterisation techniques such as SEM imaging, optical microscopy and X-ray diffraction, the microstructural changes occurring in the BMG after severe grinding passes could be identified. It is shown that crystallisation can be detected below the grinded surface even for relatively small depth of cut. The results obtained on this peculiar composition help to propose a more generic methodology to safely use grinding on BMG.