Advances in processing Titanium-based sulfur bearing BMGs by laser based powder bed fusion

Laser-based powder bed fusion of metals (PBF-LB/M) has enabled the manufacturing of demanding materials. By functionalizing the inherently high cooling rates of the process, the fabrication of bulk metallic glasses (BMGs) has become feasible. These materials exhibit exceptional properties, including an elastic limit of up to 2-3%, and an advantageous strength-to-weight relation. However, despite cooling rates of 106 K/s exceeding the critical cooling rate of BMGs drastically, the alloy selection is still limited. While significant progress has been made with good glass-formers such as Zr-based alloys, the manufacturing of alloys with lower glass-forming ability remains challenging. In this work, we investigate the processing conditions for a Ti-based sulfur containing BMG, which possesses a markedly lower critical cooling thickness of approximately 1 mm. This alloy offers an attractive combination of biocompatibility, corrosion resistance, and high wear resistance; however, the limited glass-forming ability poses significant challenges for PBF-LB/M. The impact induced by tailored processing parameters is evaluated, including the variation in laser power, scanning velocity, layer thickness, and the application of inter-vector delay times. A detailed analysis of the achievable cooling rates is provided by pyrometry. The cooling rates fulfil the theoretical requirements for vitrification. The impact on the resulting amorphicity is assessed by differential scanning calorimetry and X-ray diffraction. A relative density of > 99.5 % and amorphicity similar to cast materials are achieved, however, cracks are observed in the manufactured samples. Our findings contribute to a deeper understanding of processing parameter - microstructure relationships in PBF-LB/M of BMGs with low glass-forming ability.