Preparation of high density WRe/TZM gradient composites
WRe alloy is an alloy composed of W and Re. Tungsten has a high melting point, high high temperature strength, good heat dissipation performance, and high atomic number. Under electron bombardment, Tungsten can stimulate strong X-ray rays. The recrystallization temperature of Re is 500℃ higher than that of W, and there is no plastic-brittle transition temperature of Rhenium. Therefore, the addition of Rhenium can significantly improve the room temperature brittleness of Tungsten, reduce the plastic-brittle transition temperature, and enhance the mechanical properties of Tungsten at a certain high temperature region. With the rapid development of national defense industry and national economy, WRe alloy parts are increasingly widely used in various fields, such as rocket engine nozzle, nuclear fuel storage and control device, extreme environment thermocouple and CT X-ray tube anode target target surface material. TZM alloy is a kind of superalloy formed by adding less than 1% Ti and Zr into Mo matrix. Compared with pure molybdenum, TZM alloy has higher recrystallization temperature and high temperature strength. TZM alloy is widely used, such as non-ferrous metal die casting mold, valve body on torpedo engine, rocket nozzle, CT machine X-ray tube anode target matrix, etc. WRe/TZM composite has good joint performance due to the characteristics of W and Mo, so the advantages of WRe alloy and TZM alloy are integrated.
The scanning part of CT equipment is mainly composed of X-ray tube, detector and scanning frame. The performance of CT machine depends largely on the quality of X-ray tube, and the anode target is the key part of X-ray tube, which directly affects the emission performance and service life of X-ray tube. During X-ray tube operation, the anode target is bombarded with high-energy electron beam and emits X-rays. However, the energy conversion efficiency of the X-ray tube is very low, only about 2%, and more than 98% of the energy is converted into heat energy, and the heat is mainly concentrated on the anode, and the local temperature can reach 2600℃. Therefore, the target surface material is not only required to have the ability to generate X-ray. At the same time, it is required to have the characteristics of high temperature resistance, high thermal impact and good heat dissipation performance. Therefore, WRe alloy is usually selected as the target surface material, TZM alloy and graphite as the matrix support materials. However, the preparation of WRe/TZM composites is the main difficulty of target preparation. At present, the preparation methods mainly include powder metallurgy, powder metallurgy plus forging and vapor deposition. 106531599 a patent "one kind of X ray tube with tungsten rhenium - molybdenum alloy rotating anode material and its preparation method exposes applying tungsten-rhenium alloy powder and molybdenum alloy powder as raw material, through molding, high temperature sintering, hot isostatic pressing, straightening process preparation of anode material such as plastic materials, but its technology is complex, high cost, density is also to meet the requirements. WRe/TZM composites are prepared by powder metallurgy and forging in many countries. The density can meet the requirements of the target material, but the process is relatively complicated and the cost is high.
Therefore, a simple and effective method for fabricating WRe/TZM composites suitable for rotating anode targets is urgently needed.
