Speaker
Description
Zr-based bulk metallic glasses show high glass forming ability and are attractive base materials for near future additive applications. A new composition was printed by in-situ alloying from elemental powders via selective laser melting. In order to obtain a glassy, crack-free and dense bulk parts, a wide range of laser and scanning parameters were used and optimized. An SLM machine equipped with CO2 laser resulted in different amounts of un-melted Zr powder residues at both low and high energy density levels. Microscopic results indicate a positive trend with respect to the fraction of un-melted Zr powder for higher energy densities. However, the production of thoroughly melted and homogenized parts remains an open challenge. Segregation of Zr powder and its chemical deviation inhibited the formation of a fully glassy structure, although the cooling rates achieved during processing were much higher than the ones required to obtain fully amorphous structures. The result of this parameter study confirms that with respect to the formation of a glassy structure several challenges have to be addressed. The process optimization has to involve customization of every single parameter e.g. in terms of raw powder specification, spot size (energy distribution) and substrate material for each new composition.