Abstract: To achieve higher density of pure tungsten products at lower sintering temperatures, the powder injection molding W parts are sintered by active sintering technique with element addition. The effects of doped elements on the microstructure, micro-fracture and density are investigated by scanning electron microscope(SEM), transmission electron microscope(TEM) and Archimedes measurement. The results show that Ni can improve the density of tungsten products significantly at the low temperature sintering, and Y2O3 has an obvious effect density increase of tungsten products at the high temperature sintering. A small amount of Ni addition can reduce the sintering temperature. With 0.8% Ni addition, the density of W reaches 99.12% at a sintering temperature of 1 580 ℃ in wet H2-atmosphere. Adding a small amount of Y2O3 can also increase the density of W and reduce the grain size. The density of W achieves 95.15% after sintered at 2 280 ℃ for 0.3% Y2O3 addition. The sintering mechanism is discussed. The interface reaction between Y and W at high temperatures reduces the free energy of system and promotes the sintering process．

Key words: Active sintering, Powder injection of molding, Pure tungsten