Inconel alloys are oxidation and corrosion resistant materials well suited for service in extreme environments. When heated, Inconel forms a thick, stable, passivating oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high temperature applications where aluminum and steel would succumb to creep as a result of thermally-induced crystal vacancies (see Arrhenius equation). Inconel's high temperature strength is developed by solid solution strengthening or precipitation strengthening, depending on the alloy. In age hardening or precipitation strengthening varieties, small amounts of niobium combine with nickel to form the intermetallic compound Ni₃Nb or gamma prime (γ'). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures.

Inconel is often encountered in extreme environments. It is common in gas turbine blades, seals, and combustors, as well as turbocharger rotors and seals, electric submersible well pump motor shafts, high temperature fasteners, chemical processing and pressure vessels, heat exchanger tubing, steam generators in nuclear pressurized water reactors, natural gas processing with contaminants such as H₂S and CO₂, firearm sound suppressor blast baffles, and Formula One and NASCAR exhaust systems.^[8][9] Inconel is increasingly used in the boilers of waste incinerators^[10]. The Joint European Torus vessel is made in Inconel^[11]. Inside JET a plasma is heated to temperatures that are higher than those found in the Sun. A strong magnetic field keeps the plasma away from the vessel.