Process for making oxide dispersion-strengthened tungsten heavy alloy by mechanical alloying

Abstract

Disclosed is a process for making an oxide dispersion-strengthened tungsten heavy alloy by mechanical alloying that includes the steps of: adding 0.1 to 5 wt. % of Y2O3 powder to a mixed powder comprising more than 90 wt. % of tungsten powder, and nickel and iron powders for the rest; and subjecting the resulting mixture to a mechanical alloying to prepare an oxide dispersion-strengthened tungsten heavy alloy powder. The oxide dispersion-strengthened tungsten heavy alloy prepared by the mechanical alloying is characterized in that fine Y2O3 particles are uniformly dispersed in the matrix which are stable at high temperatures results in enhanced high-temperature strength and a reduction of the shearing strain of the fracture during high-speed shear deformation.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to a process for making an oxide dispersion-strengthened tungsten heavy alloy mainly used for an amour-plate-destroying warhead by mechanical alloying.[0003] 2. Description of the Related Art[0004] Tungsten heavy alloy is mainly comprised of 90 to 98 wt. % of tungsten to use the high-density property of the tungsten, and nickel and iron for the rest at a weight ratio of 7:3 to 8:2 to enhance the sintering property and processability. Such a tungsten heavy alloy has a fine structure in which body-centered cubic (BCC) spherical tungsten grains with a particle size of 30 to 40 .mu.m are dispersed in the face-centered cubic (FCC) W--Ni--Fe matrix. The tungsten heavy alloy possesses excellent mechanical properties, for example, high density of 16 to 18.5 g / cm.sup.2, high tensile strength of 800 to 1200 MPa and elongation percentage of 20 to 30% and is broadly used as a material for the balanced supports of aircrafts, ra...

AI Technical Summary

Benefits of technology

[0012] The oxide dispersion-strengthened tungsten heavy alloy prepared by the mechanical alloying is characterized in that the fine Y.sub.2O.sub.3 particles are uniformly dispersed in the matrix. The addition of the Y.sub.2O.sub.3 particles stable at high temperatures results in enhanced high-temperature strength and a reduction of the shearing strain of the fracture during high-speed shear deformation, based on which fact, a technique has been developed to control the mechanical properties of the oxide dispersion-strengthened tungsten heavy alloy by varying the added amount of the Y.sub.2O.sub.3.

[0016] The tungsten alloy powder obtained by the mechanical alloying method of the present invention is then compacted under a pressure into a compressed powder and then subjected to a sintering in the temperature range of 1400 to 1600.degree. C. The sintering temperature below 1400.degree. C. hardly achieves sufficient sintering and reduces the relative density of the final product with a deterioration of the mechanical properties, whereas the sintering temperature above 1600.degree. C. excessively increases the liquid phase fraction and the diffusion velocity to result in a rapid growth of the tungsten grains with a deterioration of the mechanical properties.

Problems solved by technology

The amour-plate-destroying piercer made from depleted uranium is excellent in the piercing ability but currently limited in its use because it is disadvantageously poor in processability and abrasion resistance and, especially, incurs radioactive contamination.

However, there is still no report on the systematic research on the process for making the oxide dispersion-strengthened tungsten heavy metal, in particular, enhancing the self-sharpening by the oxide dispersion.

% rather results in a deterioration of the mechanical properties and mechanical processability.

The sintering temperature below 1400.degree. C. hardly achieves sufficient sintering and reduces the relative density of the final product with a deterioration of the mechanical properties, whereas the sintering temperature above 1600.degree. C. excessively increases the liquid phase fraction and the diffusion velocity to result in a rapid growth of the tungsten grains with a deterioration of the mechanical properties.

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