Abstract
In this study, the mechanical properties and deformation features of Zr-based bulk metallic glass (BMG) are investigated at micro-scale via in situ micro-pillar compression. Furthermore, the effects of the strain rate and micro-pillar diameter on respective stress–strain curves are investigated. Together with the mechanical properties, such unique in situ micro-pillar compression techniques provide physical status to the micro-pillars, referring to the instances of stress–strain curves. It is noted that the effect of the strain rate on the stress–strain behaviour of the BMG diminishes with increasing micro-pillar diameter. In contrast, yield and ultimate compressive strength increase with increasing micro-pillar diameter, up to 4 µm. The deformation details after compression, as a result of conformed mechanical loading, are analysed by SEM and TEM. As evident from electron microscopy investigation, the plastic deformation is evidenced by the presence of multiple slip/shear bands, acting as load accommodation mechanisms in the course of mechanical loading together and resemble local plastic flow (ductile in nature) between two shear plans.
Highlights
As pointed out later by Yavari et al [24] and Gloriant et al [25], one of the reasons behind such a discrepancy is the formation of nanocrystalline zones [26] dispersed within the bulk metallic glass (BMG), which can be either mechanical- or temperature-induced
All the pure elements (Zr, Ti, Ni, Cu and Be with 99.99% purity) with respective nominal composition of the alloy were poured in the mould and melted by arc in an inert furnace filled with argon gas
The BMG is homogeneous in nature and there is no existence of any defects, such as the porosities and the cavities
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. As pointed out later by Yavari et al [24] and Gloriant et al [25], one of the reasons behind such a discrepancy is the formation of nanocrystalline zones [26] dispersed within the BMGs, which can be either mechanical- or temperature-induced These discrepancies show that mechanical responses of BMGs are a complex process, and conventional macro-scale experimental procedures such as hardness testing, tensile testing and tribological behaviour etc., are not enough to investigate the fundamental deformation behaviour of such materials. Zr- and Ti-based BMG is one of the most commonly investigated materials in tribological applications, as evident in literature, due to their high glass-forming ability, together with excellent mechanical properties [27,28] In this light, the present research approach is to investigate the fundamental deformation behaviour of. The acquired knowledge from this investigation will help to attain a fundamental understanding of micro-mechanical properties of BMGs, together with the role of extrinsic size effect as well as strain rate
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