Powder metallurgy sputtering targets and methods of producing same
View Patent ↗A method of forming a sputtering target and other metal articles having controlled oxygen and nitrogen content levels and the articles so formed are described. The method includes surface-nitriding a deoxidized metal powder and further includes consolidating the powder by a powder metallurgy technique. Preferred metal powders include, but are not limited to, valve metals, including tantalum, niobium, and alloys thereof.
1. A method for forming a powder metallurgy article, comprising:
surface-nitriding a deoxidized metal powder to form a surface-nitrided metal powder having an oxygen content of about 300 ppm or less and having a nitrogen content of at least about 10 ppm;
consolidating said surface-nitrided metal powder by a powder metallurgy technique to form a metallurgical article; and
wherein said formed metallurgical article comprises a sputtering target.
2. The method of claim 1 , wherein said deoxidized metal powder comprises a valve metal.
3. The method of claim 1 , wherein said deoxidized metal powder comprises tantalum.
4. The method of claim 3 , wherein said surface-nitrided metal powder is formed having a tantalum nitride shell.
5. The method of claim 1 , wherein said deoxidized metal powder comprises niobium.
6. The method of claim 5 , wherein said surface-nitrided metal powder is formed having a niobium nitride shell.
7. The method of claim 1 , wherein said surface-nitrided metal powder has an oxygen content of 100 ppm or less and has a nitrogen content of at least about 40 ppm.
8. The method of claim 1 , wherein said deoxidized metal powder has a mesh size of from about 40 to about 400 mesh.
9. The method of claim 1 , wherein said surface-nitrided metal powder has a nitrogen content from about 100 ppm to about 1000 ppm.
10. The method of claim 1 , wherein said consolidating is at a temperature not exceeding 0.7 T H of said deoxidized metal powder.
11. The method of claim 1 , wherein said consolidating comprises compressing said surface-nitrided metal powder to from about 80 to about 100% of theoretical density with compressive forces of from about 30,000 to about 90,000 psi.
12. The method of claim 1 , wherein said powder metallurgy technique comprises hot isostatic pressing.
13. The method of claim 1 , wherein said powder metallurgy technique comprises extrusion.
14. The method of claim 1 , wherein said surface-nitriding comprises contacting with a nitrogen gas.
15. The method of claim 1 , wherein said formed metallurgical article has an oxygen content of about 300 ppm or less and has a nitrogen content of at least about 10 ppm.
16. The method of claim 1 , wherein said formed metallurgical article has an oxygen content from about 1 ppm to about 100 ppm.
17. The method of claim 1 , wherein said formed metallurgical article has a nitrogen content from about 40 ppm to about 10,000 ppm.