Pure tungsten and oxide dispersion strengthened tungsten manufactured by selective laser melting: microstructure and cracking mechanism

Abstract The microstructure and cracking behavior of pure tungsten and micron- and nanosized Y2O3 dispersion strengthened tungsten fabricated by selective laser melting are comparatively studied in this work. The pure tungsten with high density (98.3 ± 0.3%) is successfully fabricated by optimizing processing parameters, but there are still a few microcracks. The cracking mechanism of pure tungsten is attributed to the segregation of tungsten oxide impurities at the grain boundaries and the formation of high-angle grain boundaries. The agglomeration of Y2O3 occurs only in the tungsten with the addition of micron-Y2O3 while not in the tungsten with the addition of nanosized Y2O3. The addition of Y2O3 can reduce cracks due to the formation of a large number of low-angle twisted tungsten grains. The cracking mechanism of pure tungsten and the inhibition of cracking by the addition of Y2O3 proposed in this work are of great significance for the SLM manufacture of high-performance and crack-free tungsten-based alloys. Our work may also provide relevant strategy for the suppression of crack in other alloys with high melting point by SLM.