Metals in Aircraft Engines

A jet engine in an aircraft is subjected to very harsh conditions during operation, including high temperatures, vibrations, and mechanical stresses.  In order to withstand these environmental effects, jet engine components have to be manufactured using specific materials and alloys.  Each part of the engine is designed to withstand the specific conditions at that location.

Fan Blade Metallurgy

The fan blade is mounted at the inlet of the engine and helps to smooth the airflow into the engine and prevent debris from entering the engine.  Fan blades have to be strong enough to withstand the impact of a bird or runway debris, so they are made from titanium.  Each blade consists of two shells welded together, with a titanium honeycomb on the inside of the shells to increase strength while maintaining a light weight.

Compressor Disc and Blade Metallurgy

The compressor takes the incoming air and compresses it in preparation for combustion.  The central hub of the compressor is fabricated using powder metallurgy.  Each of the blades of the compressor are cast individually within a ceramic mold and bolted to the central hub.

Combustion Chamber Metallurgy

The combustion chamber is where the fuel is ignited, and has to be able to withstand the immense heat and pressures of the process.  The combustion chamber is created from a series of cast titanium sections that have additional materials added to it to increase its ductility.

Turbine Disc and Blade Metallurgy

The turbine disc and blades are made in nearly the same way as the compressor disc and blades, but because of the extreme heat of the adjacent combustion chamber, these component have to be even stronger.  Titanium is used for both the disc and the blades, but the blades are subjected to a special process called directional solidification that causes the grains of the metal alloy to be oriented all in the same direction.  This greatly increases the strength of the blade and helps it to resist fracture.  The turbine blades are finely machined to a precise shape and laser machining is used to add tiny cooling holes into the blade.

Exhaust System Metallurgy

The exhaust system allows the hot gases of the combustion process to escape the engine and to push the aircraft forward.  The interior section of the exhaust system where the temperature is highest is made from titanium, while the exterior portion of the exhaust system is made from Kevlar.