Effect of powder size on microstructure and mechanical properties of rhenium

Two kinds of rhenium powders with the different particle size distribution were prepared by jet dispersion treatment. The effects of the powder particle size and sintering temperature on the microstructure and mechanical properties of the sintered rhenium billet were studied by confocal laser scanning microscope, scanning electron microscope (SEM), Vickers hardness tester, and nano indentor. In the results, the agglomeration of rhenium powders is improved after the jet dispersion treatment, the particle size distribution of rhenium powders is narrowed, and the average particle size decreases from 21.21 μm to 9.45 μm. With the increase of sintering temperature, the number of pores in the sintered rhenium billet continues to decrease. The microstructure of the sintered rhenium billet after the dispersion treatment shows more uniform, and the average grain size at 2320 ℃ sintering temperature decreases from 10.8 μm to 9.9 μm. The relative density of the sintered rhenium billet after the dispersion treatment increases to 98.6%, which is 4% higher than untreated, and the microhardness increases by about 12%. The sintered rhenium billet after the dispersion treatment has the greater peak hardness, and the hardness is 2~5 GPa higher than that untreated.