Superalloy:

Superalloys are classified into three main categories:

1. Nickel-Based Superalloys

Nickel-based superalloys most commonly consist of nickel and aluminum and/or titanium. These alloys are widely used as turbine blades in jet engines and turbochargers due to their desirable material properties at high temperatures. An example of a nickel-base superalloy is Inconel®. Inconel® is made of nickel and chromium which results in high levels of corrosion resistance at high temperatures. Many of the industrial nickel-based superalloys contain alloying elements, including chromium (Cr), aluminum (Al), titanium (Ti), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta) and cobalt (Co).

2. Iron-Based Superalloys

Iron-based superalloys are formed of iron and nickel or chromium. Iron-based alloys are cheaper than other superalloys and are well-known for their wear resistance. Iron-based alloys are used in aircraft bearings and other applications which are subject to moving contact.

3. Cobalt-Based Superalloys

A cobalt superalloy contains 50–60% cobalt mixed with 20–30% chromium and 5–10% tungsten. Cobalt alloys have a high fatigue life and higher strength than iron- and nickel-based superalloys in high-temperature applications. Due to their high corrosion resistance, they form some of the parts of a gas turbine that are exposed to the atmosphere.

Of these three categories, nickel-based alloys have the widest range of applications, particularly in the aerospace industry.