Spherical-crystal ammonium paratungstate can be used to prepare high-performance tungsten heavy alloys, which has the characteristics of high density, good ductility, large yield strength and high tensile strength. This is because the spherical-crystal tungsten powder obtained by calcination and hydrogen reduction of spherical single-crystal ammonium paratungstate has large loose apparent density and good fluidity. And it is easy to fill the die cavity. Also, it makes the density of compact uniform.
The W-Ni-Fe heavy alloy prepared by spherical tungsten powders with particle size of less than 200nm has the following advantages:
1. Excellent performance, uniform structure, and uniform distribution of tungsten phase and bonding phase.
2. Compared with current tungsten heavy alloy, the density of W-Ni-Fe heavy alloy billet is increased by 0.5~1g/cm3, the radial shrinkage ratio after sintering is reduced to 14% or less, the tensile strength is increased by 20%, and the elastic aftereffect is reduced to 0.2~0.7%.
Therefore, the research on preparation technology and principle of spherical-crystal ammonium paratungstate is a key problem to be solved urgently.
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