Tungsten alloy parts Kinetics materials

High-density tungsten alloy, also referred to as tungsten-heavy alloy, is composed primarily of tungsten (with a mass fraction of 85% to 99%) and is alloyed with elements such as Ni, Cu, Fe to achieve densities between 16.5 and 19.0 g/cc. The most prevalent types include tungsten nickel copper and tungsten nickel iron alloys, where tungsten content ranges from 90% to 97%. The tungsten nickel copper variety is distinguished by its non-magnetic properties, in contrast to the magnetic nature of the tungsten nickel iron alloy. The latter is more commonly utilized due to its superior mechanical characteristics compared to the former.

The fabrication of high-density tungsten alloy typically follows the powder metallurgy pathway, which includes several steps:

• Powder preparation
• Blending
• Compaction
• Sintering
• Heat treatment
• Plastic deformation (through processes such as forging and rolling)
• Annealing
• Final product

Some items may be produced directly through the sintering process.

Sintering Process

For sintering high-density tungsten alloys, the liquid phase sintering technique is employed, usually setting the temperature 20 to 60 ℃ above the alloy's liquid phase. For W-Ni-Fe alloys, the sintering occurs at temperatures between 1500 and 1525 ℃, aiming for densities near theoretical values. The process typically lasts 60 to 90 minutes; durations beyond 120 minutes can degrade the alloy's qualities. Utilizing a higher sintering temperature for a shorter duration can enhance the tensile strength and ductility of the alloy. The cooling rate selection is crucial and depends on the alloy's Ni to Fe mass ratio. When this ratio avoids the formation of brittle compounds (typically between 2 and 4), the cooling rate can be adjusted without risking intermetallic compound formation, thus minimizing brittleness and porosity.

Heat Treatment

Post-sintering treatments include quenching, rapid cooling, atmospheric dehydrogenation, and surface hardening to minimize interface impurity segregation like P and S, mitigate hydrogen embrittlement, and tailor other alloy properties. These treatments refine the microstructure, enhance solid solution strengthening

, and can boost the alloy's strength significantly.

Plastic Deformation Processing

Following plastic deformation, machining processes such as turning, milling, cutting, drilling, and polishing are selected based on the specific requirements of the design drawings to achieve the final product form.