Abstract
Additive manufacturing of Zr-based bulk metallic glasses (BMGs) is subject to growing scientific and industrial attention. Laser-based powder bed fusion of metals (PBF-LB/M) becomes a key technology to overcome current restrictions of size and geometry in the manufacturing of BMGs. For industrial application, further knowledge about defect formation, such as porosity and crystallization, is mandatory to develop processing strategies and suitable quality assurance. In this context, the influence of the particle size distribution, oxygen contamination, and applied process parameters during the PBF-LB/M of the glass-forming alloy AMZ4 (in at.% Zr59.3Cu28.8Al10.4Nb1.5) on the structural and mechanical properties were evaluated. It was found that the addition of SiO2 flow aid to the feedstock is suitable to increase flowability without impeding fabrication of the amorphous material. Furthermore, the processing of partially crystalline powder particles into amorphous samples is demonstrated. It indicates that today’s high effort producing amorphous powders and thus the production costs can be reduced. Flexural bending tests and high-energy synchrotron X-ray diffraction reveal that the powder feedstock’s oxygen content is crucial for the amorphization, embrittlement, and flexural strength of PBF-LB/M processed Zr-based BMGs.
Highlights
Bulk metallic glasses (BMGs) gain rapidly increasing interest by researchers of various fields due to their unique properties such as high strength as well as wear- and corrosion resistance [1]
The present work evaluates the influence of different oxygen contents, partial crystallinity, and the usage of flow-aid in the feedstock of the commercially available gas atomized Zr-based BMG-forming alloy AMZ4 during PBF-LB/M. We investigated their impact on the applicable PBF-LB/M parameter range, the resulting structural properties, and mechanical performance
Three argon atomized powder batches of the BMG-forming alloy Zr59.4Cu28.8Al10.4Nb1.5 with mean particle sizes of 10–45 mm and varying oxygen contents from ~600–2300 mg/g were used for this study
Summary
Bulk metallic glasses (BMGs) gain rapidly increasing interest by researchers of various fields due to their unique properties such as high strength as well as wear- and corrosion resistance [1]. Their characteristic amorphous atomic structure is usually obtained by the rapid freezing of the high-temperature equilibrium liquid into the glassy state. Apart from that, the rapid laser movement and comparatively small melt volume lead to large cooling rates up to 106 K/s [8], which enables the processing of non-equilibrium and far from equilibrium materials. The heat dissipation is largely independent of the part dimensions due to the layer-wise built-up, which diminishes the current design limitations of cast BMGs [6,7,9]
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