The tungsten nickel alloy has been used in engineering applications for about fifteen years. This alloy has a high density, ductility, and excellent thermal stability. In addition, it is a great electrical conductor. It is widely used in aerospace and energy applications.
Alloys with higher nickel to iron ratios exhibit increased hardness and strength. They are also ideal for radiation shielding. However, they have lower expansion coefficients, thereby making them unsuitable for magnetism-sensitive applications. These alloys are ideal for protective components, bearing assemblies, and ballasts.
One way to improve the tensile strength of a tungsten-nickel-iron alloy is to age the material at 300deg-600deg C. After aging, the hardness is increased, and the alloy’s tensile strength is increased.
Another method to increase the hardness of a tungsten-nickel-iron-cobalt alloy is to swage the alloy. This process reduces the alloy’s area by about five to forty percent. The swage step increases the hardness of the alloy from thirty to forty points.
The tungsten-nickel-iron composite powder is pressed with a steel mold under 360 MPa pressure. The resulting sintered bar is heated in an argon gas atmosphere for one to three hours. When the sintering is complete, the residual hydrogen in the sintered bar is carried away by the flowing argon gas.
High-density quaternary tungsten-base alloys are formable at hot pressing temperatures from 1200 to 1350 deg C. They have excellent machinability and little component shrinkage.
Examples of improved high-density tungsten-nickel-iron-cobalt-aluminum alloys are shown. These include a high density alloy with a binder of about 30 to 83 percent nickel, 12 to 47.5 percent cobalt, and 5 to 40 percent iron.