TZM gradient composites
WRe alloy is an alloy composed of tungsten and rhenium. Tungsten has high melting point, high temperature strength, good heat dissipation performance and high atomic number, and can stimulate strong X-ray rays under electron bombardment, but W has a notching sensitivity effect, which is easy to lead to the expansion and deepening of cracks, so that the target substrate is peeled off. The recrystallization temperature of Re is 500℃ higher than that of W, and Re does not have a plastic and brittle transition temperature. Therefore, the addition of Re can significantly improve the room temperature brittleness of W, reduce the plastic brittleness transition temperature, and enhance the mechanical properties of W in a certain high temperature region. With the rapid development of the national defense industry and the national economy, WRe alloy parts are increasingly widely used in various fields, such as rocket engine nozzles, nuclear fuel storage and control devices, extreme environment thermocouples and target surface materials for X-ray tube anodes of CT machines. TZM alloy is a kind of superalloy formed by adding the total amount of Ti and Zr in Mo matrix, which has higher recrystallization temperature and high temperature strength than pure molybdenum. TZM alloy（Titanium Zirconium Molybdenum alloys） is widely used, such as non-ferrous metal die casting die, torpedo engine valve body, rocket nozzle, CT machine X-ray tube anode target substrate. WRe/TZM composite has good joint performance when W and Mo are connected together, so it integrates the advantages of WRe alloy and TZM alloy (Titanium Zirconium Molybdenum alloys).
The scanning part of CT equipment is mainly composed of X-ray tube, detector and scanning frame. The performance of CT machine depends on the quality of X-ray tube to a large extent, and the anode target is the key component of X-ray tube, which directly affects the emission performance and service life of X-ray tube. When the X-ray tube is working, the anode target is bombarded by a high-energy electron beam and emits X-rays. However, the energy conversion efficiency of the X-ray tube working process is very low, about only about 2%, about 98% of the energy is converted into heat, and the heat is mainly concentrated on the anode, its local temperature can reach 2600℃, so the target surface material not only requires its ability to produce X-rays, At the same time, it is required to have the characteristics of high temperature resistance, large thermal shock and good heat dissipation performance. Therefore, the anode target is usually selected WRe alloy as the target surface material, TZM alloy and graphite as the matrix support material.
