titanium niobium is an alloy of titanium and niobium, used industrially to make superconducting magnet wire for type II superconducting magnets. These are used in liquid-helium-cooled magnetic fields, for example at the International Space Station and in the Wendelstein 7-X stellarator. The alloy has a high critical current density and the highest practical temperature at which it can be made to work, making it useful in high-energy physics experiments.
Niobium, the second element in the periodic table, is found in pyrochlore and columbite, its two principal commercial sources. It is a silver-white metal with a melting point of 1,870 deg C and boiling point of 3,300 deg C. It has five natural isotopes: 46Ti through 50Ti, the most abundant being 48Ti. Its chemical properties are similar to those of zirconium, and it is soluble in dilute sulfuric acid.
Alloys of titanium and niobium can be made to exhibit shape memory behavior by appropriate thermo-mechanical processing. For example, the zero load Ms temperature of an alloy consisting of essentially 44 atomic percent titanium, 47 atomic percent nickel and 9 atomic percent niobium was determined as a function of processing conditions. Samples were warm worked and warm annealed to varying temperatures, hot worked at temperatures between 400 deg and 600 deg C and then cold elongated. The recovery force was then measured and plotted as a function of the elongation ratio, with the Ms temperatures of martensite and austenite recorded before and after recovery.