Tungsten alloy part, and discharge lamp, transmitting tube, and magnetron using the same
It is an object to provide a tungsten alloy exhibiting characteristics equal to or higher in characteristics than those of a thorium-containing tungsten alloy, without using thorium which is a radioactive material, and a discharge lamp, a transmitting tube, and a magnetron using the tungsten alloy. According to the present invention, a tungsten alloy includes 0.1 to 5 wt % of Zr in terms of ZrC.
1. A method for producing a tungsten alloy part, the method comprising:
mixing raw powders comprising ZrC powder having an average primary particle diameter of 15 μm or less, and tungsten powder having an average particle diameter of 0.5 to 10 μm,
preparing a molded body of the raw powders, and
sintering the molded body, thereby decarbonizing the ZrC powder,
wherein the content of the ZrC powder in the raw powders falls within a range of 0.1 to 5 wt %, and
the tungsten alloy parts comprises ZrC and Zr, and contents of Zr, ZrC and C are expressed in ZrC x where x<1.
2. The method according to claim 1 , wherein the average primary particle diameter of the ZrC powder is equal to or smaller than the average particle diameter of the tungsten powder.
3. The method according to claim 1 , wherein the sintering is performed at a temperature of 1400 to 3000° C. for 1 to 20 hours.
4. The method according to claim 1 , wherein the sintering comprises presintering the molded body at a temperature of 1250 to 1500° C. to obtain a presintered molded body, and electric sintering the presintered molded body at a temperature of 2100 to 2500° C.
5. The method according to claim 1 , wherein the sintered molded body has a cylindrical shape, the method further comprising performing processing process of at least one selected from the group consisting of a forging process, a rolling process, a wiredrawing process, a cutting process, and a polishing process to the molded body after the sintering.
6. The method according to claim 5 , wherein a processing ratio by the processing process falls within a range of 30 to 90%, and the processing ratio is represented by [(A−B)/A]×100%, where A is a sectional area of the cylindrical sintered body before the processing process and B is a sectional area of the cylindrical sintered body after the processing process.
7. The method according to claim 5 , which further comprising performing a stress relief heat treatment to a processed molded body at a temperature of 1300 to 2500° C.
8. The method according to claim 1 , wherein contents of Zr, ZrC and C are expressed in ZrC x where 0<x<1.
9. The method according to claim 1 , wherein contents of Zr, ZrC and C are expressed in ZrCx where 0.2<x<0.7.
10. The method according to claim 1 , wherein the tungsten alloy part is used for a discharge lamp part, a transmitting tube part, or a magnetron part.