The simultaneous improvement of strength and ductility of the 93W-4.6Ni-2.4Fe prepared by additive manufacturing via optimizing sintering post-treatment

Abstract The influence of sintering post-treatment temperature on the microstructure and mechanical properties of 93 W-4.6Ni-2.4Fe (wt%) tungsten heavy alloy prepared by powder extrusion 3D printing has been examined. The density of the specimen gradually increases to over 99.5% with the increase of the sintering temperature. The contiguity first decreases with increasing temperature and then increases, which is mainly related to the evolution of the distribution of γ phase and the tungsten particle size. The fracture mode of the 93W-4.6Ni-2.4Fe specimen changes from brittle fracture for the sintering temperature of 1430 °C to ductile fracture for the sintering temperature range of 1450–1480 °C. The sintering temperature of the 93 W-4.6Ni-2.4Fe specimen with the highest tensile strength (1040 ± 6 MPa) and elongation (20.7 ± 0.4%) is determined to be 1480 °C. The high ductility of the specimen sintered at 1480 °C can be attributed to the formation of high-density uniformly distributed dimples in the network γ phase and the bridging effect of γ phase on the cracks. The high strength is related to the high density of specimen, moderate contiguity, suitable tungsten particle size and solid solution strengthening effect.