Ferrous Superalloys: Superalloy, or high-performance alloy, is an alloy with superior mechanical strength, good surface stability, corrosion resistance, and can withstand high temperatures without oxidizing or losing mechanical properties. Typical applications are in aerospace industry, eg. for turbine blades for jet engines.
Superalloys are typically based on nickel, cobalt, or iron. Many other elements, both common and exotic, can be present; chromium, molybdenum, tungsten, aluminum, zirconium, niobium, rhenium, carbon or silicon are just a few examples.
Single-crystal superalloys (SC superalloys) are designed to have some strength even when formed as a single crystal, so there are no grain boundaries in the material. The mechanical properties of most other alloys depend on the presence of grain boundaries, but at high temperatures they would participate in creep and must be replaced by other mechanisms. In many such alloys, islands of an ordered intermetallic phase sit in a matrix of disordered phase, all with the same crystalline lattice. This approximates the dislocation-pinning behavior of grain boundaries, without introducing any amorphous solid into the structure.
Examples of superalloys are Hastelloy, Inconel, MP98T, TMS-63, TMS-71, and TMS-75.