Claims
- 1. A method for forming a homogeneous W--Cu pseudoalloy comprising pressing a tungsten-coated copper composite powder to form a compact and sintering the compact, the tungsten-coated copper composite powder comprising individual particles having a tungsten phase and a copper phase wherein the tungsten phase substantially encapsulates the copper phase.
- 2. The method of claim 1 wherein sintering the compact comprises forming a sintered tungsten framework in a solid-state sintering stage followed by internal infiltration of the sintered tungsten framework by liquid copper during a liquid-phase sintering stage.
- 3. The method of claim 1 wherein the compact is sintered without copper bleedout.
- 4. The method of claim 3 wherein the sintering comprises subjecting the compact to a temperature cycle, the temperature cycle comprising (1) increasing temperature from ambient temperature to a temperature sufficient to cause solid-state sintering, (2) slowly increasing the temperature at a rate of about 1.degree. C./minute to about 5.degree. C./minute until liquid-phase sintering begins, and (3) increasing the temperature to a temperature sufficient to complete densification of the compact.
- 5. The method of claim 4 wherein the temperature sufficient to complete densification is from 1150.degree. C. to 1600.degree. C.
- 6. The method of claim 5 wherein the temperature sufficient to complete densification is determined by the amount of copper in the tungsten-coated copper composite powder.
- 7. The method of claim 1 wherein the tungsten-coated composite W--Cu powder is mixed with a binder prior to pressing.
- 8. The method of claim 1 wherein sintering the compact comprises (1) removing a binder from the compact at 300-500.degree. C.; (2) oxygen removal from the compact at 800-950.degree. C.; (3) solid-state sintering of a tungsten framework at a very low rate of temperature increase in the range of 950-1080.degree. C.; (4) oxygen removal from molten copper at 1080-1130.degree. C.; and (5) internal infiltration of the tungsten framework and densification of the pseudoalloy at 1150-1600.degree. C.
- 9. The method of claim 8 wherein the rate of temperature increase during the solid-state sintering is from about 1.degree. C./minute to about 5.degree. C./minute.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of application Ser. No. 08/559,903, filed on Nov. 17, 1995, which is a continuation-in-part of application Ser. No. 08/362,024 now U.S. Pat. No. 5,468,457 and Ser. No. 08/361,415 now U.S. Pat. No. 5,470,549, both filed Dec. 22, 1994, the disclosures of which are incorporated herein by reference.
US Referenced Citations (9)
Foreign Referenced Citations (1)
Number |
Date |
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4-371373 |
Feb 1992 |
JPX |
Related Publications (1)
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Date |
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361415 |
Dec 1994 |
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Divisions (1)
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559903 |
Nov 1995 |
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Continuation in Parts (1)
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362024 |
Dec 1994 |
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