Selective Laser Melting of W–Y2O3 Powder with Submicron Particle Structure Spheroidized in Thermal Plasma Flow

For the first time, the possibility of using powder of the W–Y2O3 system with a fraction of “5–50” μm with a spherical particle shape and a tungsten grain size of 0.1–3.0 μm obtained using plasma-chemical synthesis, granulation, and spheroidization methods, in additive manufacturing technologies for the creation of products with complex geometry is demonstrated. The influence of technological parameters of the selective laser melting (SLM) process on physical and mechanical characteristics and microstructure of test samples made of W–Y2O3 powder is studied. It is found that the maximum values of density, hardness by Vickers, and microhardness of SLM samples of the W–1.2 wt % Y2O3 system are 18.3 g/cm3 (relative density is 98.4%), 315 kgf/mm2, and 4.5 GPa, respectively. The SLM samples in all processing modes have a similar heterogeneous dendritic microstructure. The average conventional grain size of tungsten ranges from 5 to 30 μm. The material has microcracks and micropores in most production modes due to high crystallization rate and large temperature gradient during the SLM process. On the basis of the results of studies of density, hardness, and microhardness of obtained products, the optimization of the main technological parameters of SLM process (laser radiation power and scanning speed) is carried out.