The article discusses the possibilities of preparing high-quality powder materials from heat-resistant light alloys based on refractory monoaluminides of nickel β-NiAl and ruthenium β-RuAl for the manufacture of compact samples/products of complex shape using additive technologies with minimal final machining. Additive technologies are based on the use of spherical precursor micro-powders with a regulated granulometric composition, good fluidity and an oxide-free surface. The possibilities of obtaining precursors from RuAl-based alloys by plasma spheroidization of powders obtained by crushing mixtures from scrap samples of alloys based on RuAl with various additives are considered.
A method for obtaining nanopowder microgranules of the W – Ni – Fe system (composition of the VNJ-90) of a micron size range by spray drying of a suspension based on composite nanoparticles obtained by plasma chemical synthesis is considered. The parameters of operation of the Buchi Mini Spray Dryer B-290 spray drying laboratory unit with an ultrasonic nozzle have been experimentally determined, providing for the production of nanopowder microgranules of VNJ-90 with an output of the target fraction of 25 – 63 µm at the level of 65 %. The dependence of the size and morphology of the obtained granules on the choice of the dispersion medium, the concentration of the dispersed phase and the organic binder in the suspension is established. The effect of the suspension flow rate during spray drying on the yield of granules of a fraction of 25 – 63 µm was evaluated. The test of the manufactured experimental sample of nanopowder microgranules in the process of plasma spheroidization was carried out.
The powder of 93 W – 4.9 Ni – 2.1 Fe (VNZh-93) pseudo-alloy with a spherical particle shape in the size range of 15 – 50 μm with a grain size of 0.5 – 3 μm was obtained using plasma chemical synthesis, granulation and spheroidization technologies. The possibility of using spheroidized powder VNZh-93 in additive 3D-printing is demonstrated. Studies of the physical and mechanical characteristics and microstructure of VNZh-93 test samples made using the selective laser melting technology (SLM) have been carried out. It is shown that the parameters of the SLM significantly affect the formation of the microstructure of test samples. It is possible to form a homogeneous equiaxed microstructure with an average grain size of about 1 micron using optimal SLM modes. It is shown that maximum density and Vickers hardness of VNZh-93 obtained in optimal SLM modes are 16.8 g/cm3 and 480 HV, respectively. These values are not inferior to the values for VNZh-93 samples obtained using traditional liquid-phase sintering technology. At the same time, the main problem of selective laser melting of VNZh-93 powder is the heterogeneity of the bulk samples microstructure and the formation of microcracks and micropores in their structure.
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