On Direct Metal Laser Sintering of Functionally Graded Material with Virgin and Mixed Powder

In the recent past, several studies were reported on meta-structure-based direct metal laser sintering (DMLS) of functionally graded materials (FGM) using virgin/recycled metallic powders. But hitherto little has been reported on DMLS of meta-structure-based FGM using a combination of virgin and mixed metallic powder with a single hopper. This study outlines the use of virgin/single and mixed metallic powder for fabricating FGM using DMLS with a single hopper. The study highlights the DMLS of FGM with 17-4 precipitate hardened (PH) stainless steel (SS) virgin powder in a sandwich layer as 'Weaire-Phelan' meta-structure and mixed powder (comprising of 17-4 PH SS (90% by wt.)-Ni-625 (5% by wt.)-Ti-6Al-4V (5% by wt.) collected as waste/mixed powder from DMLS setup) as the top and bottom layers. Results suggested that the surface roughness (Ra) of 3D-printed (by DMLS) FGM was 12.66 mu m, 19.85 mu m, and 12.41 mu m for the top, middle, and bottom layers, respectively. The Ra was improved to 8.59 mu m, 12.35 mu m, and 8.67 mu m after wear testing. Further, after corrosion (in vitro) testing in simulated body fluid, Ra was observed as 13.36 mu m, 14.44 mu m, and 13.46 mu m, respectively. Overall, the wear and corrosive behavior have shown tuneable 4D characteristics for required surface properties in biomedical applications. The results are supported by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analysis.