Heavy metal alloys are pseudo-alloys of tungsten with a nickel-iron or nickel-copper matrix. They are produced by powder metal and sintering processes. Tungsten Heavy Alloys has a high density of 17-19 g/cm³. Comparable densities are only reached by gold or platinum. These alloys are used as mass balancing weights and attenuators in aircraft construction, in motors and power trains, as oscillating weights and centrifugal weights in machines and in equipment construction, and in medical technology for both protection from and focusing of ionizing radiation in x-ray and measuring devices.
Zirconium is mainly used as a refractory and opacifier, although small amounts are used as an alloying agent for its strong resistance to corrosion. Zirconium alloys can be found in pipes, fittings and heat exchangers, catalytic converters, furnace bricks, lab crucibles, surgical instruments, television glass, removing residual gases from vacuum tubes
Like Niobium, Tantalum is a heat-tolerant refractory metal with excellent corrosion resistance. Often alloyed with other metals, tantalum is used to make super alloys used in chemical processing, jet engines and nuclear reactors. Its oxidation properties also make it an excellent choice for many electronic applications, including electrolytic capacitors and high-power resistors. Tantalum is also highly bio-compatible and used extensively for medical applications, such as skull plates, hip joints, suture clips and stents.
Niobium (also known as columbium) is a shiny, ductile metal primarily used in alloys. It improves the properties of steel and is often used in gas pipelines, jet engines and structural applications. Because of its corrosion resistance and ability to perform at high temperatures, niobium metal plates, rods and sheets are used in sputtering targets and chemical processing equipment. At extremely low temperatures, it becomes superconductive. Superconductive niobium wire is used to make extremely powerful electromagnets used in magnetic resonance imagery and particle accelerators.
Tungsten has the highest melting point of all metals and, at temperatures greater than 1650°C, the highest tensile strength. Its thermal expansion rate is similar to that of borosilicate glass and silicon. Tungsten’s good thermal and electrical conductivity make it an excellent choice for microprocessor applications. It is also used in electron emitters, heater coils, cathode ray tubes, electrical contacts and a variety of high-heat applications.
The addition of rhenium to molybdenum improves plasticity and weldability and decreases brittleness for certain temperature ranges. It is used throughout the aerospace and electronics industries for applications such as nuclear reactors, semiconductors, electrical contacts, filaments and igniter wires.
For use in extremely high-heat environments, type C thermocouples are made from alloys containing different rhenium-tungsten ratios. Rhenium-Tungsten is also used in traditional tungsten applications when greater ductility is desired.
Constantan is a copper-nickel alloy used in a variety of thermocouple applications. It is paired with iron, copper and Chromel® to form types J, T and E thermocouples, respectively. Known for its high electrical resistivity and its ability to perform consistently despite changes in temperature, Constantan is also widely used throughout the electronics industry.
Used with Alumel® in type K thermocouples and with Constantan in type E thermocouples, Chromel® is made of nickel and chromium.
Used in conjunction with Chromel® in type K thermocouples, Alumel®1 is made of nickel, manganese, aluminum and silicon.
200 Series are chromium-manganese-nickel alloys, which maximize the use of manganese and nitrogen to minimize the use of nickel. 200 Series Nickel has good mechanical properties and excellent corrosion resistance to alkalis. It also has good electrical, thermal and magneto-strictive properties.