Views:4 Author:Site Editor Publish Time: 2020-04-26 Origin:Site
Molybdenum alloy is a non-ferrous alloy composed of molybdenum as a matrix and other elements added. The main alloying elements are titanium, zirconium, hafnium, tungsten and rare earth elements. The elements of titanium, zirconium, and hafnium not only solid-solution strengthen the molybdenum alloy and maintain the low-temperature plasticity of the alloy, but also form a stable and dispersed carbide phase to increase the strength and recrystallization temperature of the alloy. Molybdenum alloy has good thermal conductivity, electrical conductivity and low expansion coefficient. It has high strength at high temperature (1100 ～ 1650 ℃) and is easier to process than tungsten. It can be used as the grid and anode of the electron tube, the support material of the electric light source, and used to make die casting and extrusion molds, parts of the spacecraft, etc. Because molybdenum alloy has low temperature brittleness and welding brittleness, and high temperature is easy to oxidize, its development is limited. The industrially produced molybdenum alloys include molybdenum titanium zirconium series, molybdenum tungsten series and molybdenum rare earth series alloys. The main strengthening methods of molybdenum alloys are solid solution strengthening, precipitation strengthening and work hardening. Through plastic processing, molybdenum alloy sheets, strips, foils, pipes, rods, wires and profiles can be produced, and their strength and low-temperature plasticity can also be improved.Molybdenum alloys have shortcomings such as low-temperature brittleness, welding brittleness, and high-temperature oxidation, so their development is limited. It is difficult to improve the high-temperature oxidation resistance of molybdenum alloys by alloying methods, and currently only protective coatings are used to improve this performance. The main problems in the study of molybdenum alloys are to increase the high-temperature strength and recrystallization temperature and improve the low-temperature plasticity of the material. The main problem in the study of pure molybdenum materials is to improve the low-temperature plasticity, that is to reduce its plastic-brittle transition temperature.
The main strengthening methods of molybdenum alloys are solid solution strengthening, precipitation strengthening and work hardening (see metal strengthening). Titanium, zirconium and hafnium are the main alloying elements of molybdenum. The effect of alloying elements on the hardness of the rolled bar of molybdenum is shown on the next page. Titanium, zirconium and hafnium can not only solid solution strengthen and maintain the low-temperature plasticity of the material, but also form a stable and dispersed carbide phase to improve the strength and recrystallization temperature of the material.