Spherical ultrafine ammonium paratungstate, or spherical single crystal ultrafine ammonium paratungstate (APT), is the key powder material for fabricating high-density alloys with high performance. More specifically, the spherical ultrafine APT is calcined to obtain tungsten oxide, and spherical tungsten powder is prepared after hydrogen reduction of tungsten oxide. The prepared spherical W powder has the advantages of high bulk density, good fluidity and easy filling of film cavity. Also, it makes the compact have uniform density. So it can be used to produce high performance tungsten-based alloy, with the characteristics of high density, good elongation, high yield and tensile strength.
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The researchers used spherical ultrafine APT powder as a raw material to prepare spherical tungsten powder with F.S.S.S particle size less than 200nm. And the obtained spherical W powder is used to produce W-Ni-Fe alloy with uniform performance, uniform structure and uniform distribution of tungsten phase and bonding phase. Compared with the current high-density alloy, the density of such a tungsten alloy billet is 0.5-1g/cm3, the elastic aftereffect is reduced to 0.2%-0.7%, the radial shrinkage after sintering is reduced to below 14%, and the tensile strength is increased by 20 %. Therefore, the research on the preparation technology and principle of spherical ultrafine ammonium paratungstate is a key problem to be solved urgently.