They are usually divided into two broad categories:
1. Tungsten nickel copper alloy: Ni and Cu form solid solutions (or matrix phases). Cu can reduce the solubility of W in solid solution and avoid the formation of intermetallic compounds such as tungsten nickel, eight Y and Ni. It can also reduce the melting point of solid solution and ensure that the W phase is better infiltrated by matrix. Ni: Cu in alloy composition is mostly 3: 2.
2. Tungsten nickel iron alloy: The Ni:Fe in the alloy composition is 7: 3. The vacuum heat treatment can improve the mechanical properties, and can make the strength of the alloy obviously improved. In addition, according to the use requirements, W- Ni- Mo, W-Ni-Cr, and W-Ni-Co alloy have been developed.
High density tungsten alloys are usually made by pressing and sintering rod powders. In the sintering process, the sintering temperature is higher than the melting point of the matrix phase in the alloy, resulting in the liquid phase, accelerating the sintering process of the alloy, and rapidly making the densification of the alloy be close to the theoretical density. To further improve the properties of the alloy, heat treatment and plastic processing are also adopted. The alloy structure is often improved by rotary forging in industry. High density tungsten alloy has high density, high strength, plasticity and cutting wins good, good electric conductivity and thermal conductivity, low coefficient of expansion, corrosion resistance and good oxidation resistance, excellent absorption ability to rays and good weldability, which is mainly used as gyro rotor material, balance weight material, penetrator core material, core mold, fixture material, shielding materials and instrument materials.
