Preparation of Large-size Tungsten-Based Heavy Alloy

Large-size tungsten-based heavy alloy has a series of advantages including high density, low coefficient of thermal expansion, good oxidation resistance and corrosion resistance, etc. In fields of aerospace, electronic information and so on, large-size and high performance tungsten-based heavy alloy is in urgent need. Find the rule of internal structure of large-size tungsten based high specific gravity alloy during liquid phase sintering process to obtain high homogeneity, high performance and parts of large-size tungsten based high specific gravity alloy.

After analyzing the composition, sintering process, material property, microstructure and fracture surface of tungsten-based heavy alloy, four conclusions of preparation can be drawn as follows:

1.0 Adding Co and Mn elements to the tungsten-based heavy alloy can improve the property of the binder phase, enhance the wettability of the matrix relative to the tungsten particle, and increase the bonding strength of the interface between the tungsten particle and the matrix phase, then can increase the elongation of the alloy.

2.0 During the liquid phase sintering process of large-size tungsten-based heavy alloy material, the shrinkage deformation of each part is affected by the shape, size, unit weight of the material and shows different results. The radial shrinkage on the same level is also affected by the total height and quality of the product. The height is higher and the quality is heavier, the smaller the radial shrinkage of the bottom of the product is, and the greater the radial shrinkage of the upper part of the product is.

3.0 After 4 tons of 1400mm tall and large cone-shaped tungsten-based high-density alloy products are prepared by multi-step sintering and special heat treatment, the top and bottom of the material are sampled, the tensile strength of the material is more than 920MPa, and the elongation exceeds 20%.

4.0 During the liquid phase sintering process of super-mass and super-size tungsten-based heavy alloy, due to the flow of the top binder phase of the product under the action of gravity, the binder phase on top is less than that on bottom, therefore the bottom part of the binder phase is slightly less torn, the elongation of the material is slightly lower, and this deviation can be decreased by special sintering technology.

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