Preparation of high density tungsten alloy

Tungsten alloy is a kind of two-phase alloy with high density (≥16.5g/cm3), also known as high-density tungsten alloy. High density tungsten alloys are widely used not only in aviation, aerospace, weapons and other military fields, but also in civil and industrial fields.

he picture shows the fine embryo of tungsten steel plate

Tungsten alloy is a kind of two-phase alloy with high density (≥16.5g/cm3), also known as high-density tungsten alloy. High density tungsten alloys are widely used not only in aviation, aerospace, weapons and other military fields, but also in civil and industrial fields. The preparation process of high-density tungsten alloy is as follows:

1. Composition design

Tungsten content in high density tungsten alloys is generally 85-98wt%. In addition to W, Ni, Fe(Cu, etc.) are the elements with high density tungsten alloy content. In the preparation of high density tungsten alloys, elements or compounds such as Mo, Ta, Re and La are added.

2, pulverizing

Alloys with excellent mechanical properties can be prepared by using powders with high purity, small particle size and good uniformity. In the field of powder-making, nano-powders are a research hotspot, mainly including the following two categories:

1) spray drying method

Spray drying method is preferred to prepare the original salt solution with certain components. The salt solution includes tungstate and metal chloride, etc. Due to the rapid evaporation of solvent and rapid deposition of solute in small droplets, powder crystals with uniform chemical composition can be obtained.

2) mechanical alloying

Mechanical alloying method is to select a certain proportion of tungsten alloy initial powder and metal ball into the ball mill, the powder under the action of non-uniform velocity of metal ball, after cold welding and multiple deformation, finally get the composite powder with finer structure and more uniform composition.

3, forming

The traditional tungsten alloy forming process is die pressing, while the new technology is powder extrusion and powder injection. Due to the fact that these two methods mix tungsten alloy powder with forming agent and then extrude and inject it into the forming machine, they have significant advantages in preparing parts with complex shapes. Besides, powder extrusion and powder injection forming technologies are also widely applicable due to the addition of forming agent.

4, sintering

Because the solid-phase sintering method requires high size of the original alloy powder, the liquid-phase sintering method has a long sintering time and is prone to collapse and deformation. Based on their advantages and disadvantages, a two-step sintering process of solid phase sintering and liquid phase sintering was proposed. Due to the smaller deformation during two-step sintering, the obtained tungsten alloy has more uniform structure and greatly improved material properties, so two-step sintering is widely used. In addition, microwave sintering and discharge plasma sintering, which are newly developed in recent years, are also being popularized and used.