The main ways of strengthening niobium are solid solution, precipitation and deformation heat treatment. In niobium alloy, tungsten and molybdenum can improve the strength at high and low temperature, but too much of them will reduce the process performance. Tantalum is a medium strengthening element and can reduce the ductile-brittle transition temperature of the alloy. Another way to strengthen niobium alloy is to add titanium, zirconium, hafnium and a certain proportion of carbon to form dispersed carbide phase for precipitation strengthening. In addition, these active elements can also improve other properties, such as titanium alloy can significantly improve the antioxidant and process properties; Hafnium and zirconium can improve the corrosion resistance of the alloys to molten alkali metals. Hafnium can significantly improve the oxidation resistance and welding performance of the alloy. High-strength niobium alloys generally contain a large number of solid solution elements (tungsten, molybdenum, tantalum, etc.) for solid solution strengthening, and precipitation strengthening is also used to make the alloy have high strength (see metal strengthening).The plastic machining of these alloys is difficult and the deformation parameters need to be strictly controlled. In addition to nb-10w-1zr-0.1c alloy containing carbide precipitation strengthening phase, other types of medium strength alloy are added with medium content of solid solution strengthening elements to ensure excellent comprehensive performance. Low strength alloys can be guaranteed to have excellent machining properties by adding appropriate amounts of titanium, zirconium and hafnium.
Tag: niobium , Tantalum , titanium , zirconium
