Selective laser melting of Zr-based bulk metallic glasses: Processing, microstructure and mechanical properties

Abstract This study shows that large scale, complex and fully dense crack-free Zr-based bulk metallic glasses (BMGs) with high hardness, high compressive strength and a small amount of ductility can be achieved using selective laser melting (SLM). The results show that higher laser energy density leads to severe crystallisation while lower laser energy density tends to result in the formation of a fully amorphous material. By investigating the chemical distribution of the melt pool, the underlying reason for this behaviour was attributed to the chemical inhomogeneity caused by the melt flow triggered elemental segregation at high energy densities. In addition, the chemical homogeneity can be improved in some cases through the use of a multiple pass scanning strategy. The underlying mechanism is that multiple scans can result in an averaging of the melt flow within the melt pool and therefore a more homogenous distribution of the elements. More importantly, the phase formation, microstructure and mechanical properties of the SLM-fabricated Zr-based BMGs can be effectively tailored by controlling the SLM processing parameters. This provides a novel and promising route to the fabrication of large scale BMGs with complex geometry and desirable mechanical properties.