Process for producing tungsten heavy alloy billets

Details Process for producing tungsten heavy alloy billets Process for producing tungsten heavy alloy billets

1987-08-05

1988-05-17

Lechert, Jr., Stephen J.

Powder metallurgy processes

Powder metallurgy processes with heating or sintering

Powder shape or size characteristics

75248, 419 29, 419 46, 419 47, 419 53, 419 54, 419 58, C21D 100

Patent

active

047449446

ABSTRACT:
A process is disclosed for producing tungsten heavy alloy billets. The process involves forming a uniform blend of elemental powders to form a tungsten alloy having a tungsten content of equal to or less than about 91% by weight and wherein the particle size of the tungsten is no less than about 2 micrometers in diameter. This blend is uniformly packed into a container having thermal expansion similar to that of the powder. The blend is then sintered in a hydrogen atmosphere at a temperature sufficient to impart strength to the powder and to reduce oxides and remove volatile impurities from the powder without significant densification in the powder. The powder is then solid state sintered in a reducing atmosphere at a sufficient temperature to densify the powder to at least about 90% of the theoretical density but at a temperature below the liquid phase sintering temperature of the powder, to form the billet. If the tungsten content of the alloy is greater than about 88% by weight, the solid state sintered powder can then be liquid state sintered by slowly raising the temperature from the solid state sintering temperature to the liquid phase sintering temperature and holding at this temperature for a sufficient time to accomplish the liquid sintering and achieve a density of greater than about 99% of the theoretical density in the billet.

REFERENCES:
patent: 3888636 (1975-06-01), Sctertenie et al.
patent: 3979209 (1976-09-01), Snyder
patent: 3979234 (1976-09-01), Northcutt et al.
patent: 4012230 (1977-03-01), Dickinson et al.
patent: 4090875 (1978-05-01), Ludwig
patent: 4670216 (1987-06-01), Patrician
patent: 4698096 (1987-10-01), Schmidberger

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