Tungsten Heavy Alloy

Tungsten heavy Alloy generallyis two-phase composite consisting of W-Ni- Fe or W-Ni- Cu or even W-Ni-Cu-Fe. Tungsten content in conventional tungsten heavy alloys varies from 90 to 98 weight percent and is the reason for their high density (between 17 and 18.6 g/cc). Nickel, iron and copper serve as a binder matrix, which holds the brittle tungsten grains together and which makes tungsten heavy alloys ductile and easy to machine. Nickel-iron is the most popular additive, in a ratio of 7Ni:3Fe or 8Ni:2Fe (weight ratio). The conventional processing route for tungsten heavy alloys includes mixing the desired amount of elemental powders, followed by cold pressing and liquid phase sintering to almost full density. The matrix tungsten heavy alloy melts and takes some tungsten into solution during liquid phase processing, resulting in a microstructure through which large tungsten grains (20-60um) are dispersed in the matrix alloy. The as-sintered material often is subjected to thermo mechanical processing by swaging and aging, which results in increased strength and hardness in the tungsten heavy alloys.