A niobium alloy based on niobium by adding some hafnium and other elements. On the binary phase diagram, niobium and β-Hf form replacement solid solutions. Hafnium is an element, and niobium oxygen and carbonization in combination to form HfO2 and HfC compounds, play the role of dispersion strengthening, while reducing the harmful effects of gap elements, improve the weldability and coating properties of niobium alloy.
Niobium and hafnium alloys are divided into two categories according to strengthening methods: solid solution reinforced alloys and solid solution reinforced alloys combined with dispersion strengthened alloys.
Niobium hafnium alloy has good mechanical properties, weldability preparation method and processing technology including ingot preparation and plastic processing, welding, heat treatment and coating. Ingot preparation and plastic processing niobium hafnium alloy is usually prepared by the method of electron beam melting and vacuum consumable arc melting, and then extrusion or forging at temperatures above 1200℃, rolling and drawing at temperatures below 500℃, can be made into plates, strips, rods, wires and forgings and other products.
Niobium hafnium alloy has good weldability, usually using tungsten argon protection welding and electron beam fusion welding method to achieve the connection of the parent metal, but also can be used to complete the welding of niobium hafnium alloy with titanium and titanium alloy. The quality of weld is related to argon purity and vacuum degree. Generally, the higher the purity of argon and the lower the residual atmospheric pressure, the better the quality of weld.
Heat treatment: vacuum or inert gas protected annealing treatment and solution aging treatment. Layer: Cr-Ti-Si and Cr-Fe-Si are usually used as anti-oxidation coatings. The antioxidation life of niobium and hafnium alloy coated with these two coatings is more than 150h in 1371℃ air. Application: It is mainly used in the extension section of radiation cooling nozzle and thrust chamber of liquid rocket engine, fused sodium and sodium potassium alloy pressure tube and turbopump of space power generation system, high temperature structural components of jet engine, etc.
