Applications
The addition of scandium to aluminium limits the excessive grain growth that occurs in the heat-affected zone of welded aluminium components. This has two beneficial effects: the precipitated Al3Sc forms smaller crystals than are formed in other aluminium alloys and the volume of precipitate-free zones that normally exist at the grain boundaries of age-hardening aluminium alloys is reduced. Both of these effects increase the usefulness of the alloy. However, titanium alloys, which are similar in lightness and strength, are cheaper and much more widely used.
The main application of scandium by weight is in aluminium-scandium alloys for minor aerospace industry components. These alloys contain between 0.1% and 0.5% of scandium. They were used in the Russian military aircraft, specifically the MiG-21 and MiG-29.
Some items of sports equipment, which rely on high performance materials, have been made with scandium-aluminium alloys, including baseball bats, and bicycle frames and components. Lacrosse sticks are also made with scandium-titanium alloys to take advantage of the strength of titanium. The American firearm manufacturing company Smith & Wesson produces revolvers with frames composed of scandium alloy and cylinders of titanium or carbon steel.
Dentists use Erbium, chromium: yttrium-scandium-gallium garnet (Er,Cr:YSGG) lasers for cavity preparation and in endodontics.
Approximately 20 kg (as Sc2O3) of scandium is used annually in the United States to make high-intensity discharge lamps. Scandium iodide, along with sodium iodide, when added to a modified form of mercury-vapor lamp, produces a form of metal halide lamp. This lamp is a white light source with high color rendering index that sufficiently resembles sunlight to allow good color-reproduction with TV cameras. About 80 kg of scandium is used in metal halide lamps/light bulbs globally per year. The first scandium-based metal halide lamps were patented by General Electric and initially made in North America, although they are now produced in all major industrialized countries. The radioactive isotope 46Sc is used in oil refineries as a tracing agent. Scandium triflate is a catalytic Lewis acid used in organic chemistry.
Read more about this topic: Scandium