Research status of niobium-zirconium alloy

The addition of zirconium to niobium can refine the crystal grains and reduce the plasticity-brittle transition temperature; adding a small amount of carbon to the niobium-zirconium alloy, zirconium and carbon combine to form a dispersed carbide phase, which can improve the high-temperature strength of the niobium-zirconium alloy. It does not affect the plasticity and processing properties of niobium itself, and can also improve the oxidation resistance of niobium. For example, the alloy PWC-11 formed by adding 0.1% carbon to the Nb-1Zr alloy, the structure stability and creep strength are all due to Nb-1Zr alloy, the temperature is in the range of 1077~1107℃, the creep strength of PWC-11 alloy is 4 times that of Nb-1Zr alloy; niobium-zirconium alloy can resist molten alkali metal lithium, sodium, potassium and sodium-potassium alloy corrosion. Most of the niobium-zirconium alloys are used in the injectors of the thrust chambers of aerospace engines, the skins of the fuselage of the spacecraft, and the lead-through tubes of the arc tubes of high-pressure sodium lamps in the lighting industry. The niobium-zirconium alloy formed by adding zirconium to niobium has a low thermal neutron absorption cross section and is used in fast neutron reactors and space nuclear reactor fuel cladding.

With the advancement of science and technology, it is required to provide metal materials with high strength and good oxidation resistance at a high temperature of 1100~2500℃. This requires higher and higher technical requirements for niobium-zirconium alloys. Therefore, research on niobium-zirconium alloys The focus is to solve the problems of high temperature strength and high temperature oxidation resistance. The zirconium element in the niobium-zirconium alloy is to increase the strength and improve the oxidation resistance. At present, the more mature niobium-zirconium alloys mainly include Nb-1Zr, Nb-5Zr and niobium C-103 alloy. These three alloys are all low-strength and high-ductility alloys.

Niobium-zirconium alloy has a higher critical temperature Tc and critical current density Jc, and was initially used in the main products of superconducting materials. Initially, niobium-zirconium alloys with a zirconium content of 15-50% were used as superconducting materials. Although the critical temperature Tc and critical current density Jc of niobium-zirconium alloys are high, it is difficult for niobium-zirconium alloys to be less plastic than niobium-titanium alloy Processing, the raw material cost is relatively high, and then titanium is added to the niobium-zirconium alloy to produce a niobium-zirconium-titanium ternary alloy with an atomic composition ratio of 40% zirconium, 10% titanium and 50% niobium. The critical temperature Tc and critical current density Jc of the primary alloy are higher than that of the niobium-zirconium alloy, and the raw material cost is reduced. People have solved the problem of niobium-titanium alloy instability in low field in future research, and gradually replaced niobium-zirconium-titanium alloy.

Niobium-zirconium alloys do not have much development in terms of high strength and oxidation resistance, mainly by adding other alloying elements to improve high temperature strength and oxidation resistance. In recent years, a niobium-zirconium alloy target Nb-10Zr target for sputtering has been proposed from the European optical coating industry. The weight ratio of zirconium in the alloy is required to reach 10%, and the niobium-zirconium alloy target has a uniform grain structure and a compact structure. Since the content of zirconium is as high as 10%, the plasticity of its alloy is greatly affected, and the processing performance is greatly reduced.