Superalloys

The term "superalloys" is generally reserved for austenitic alloys which, when used at high temperatures in excess of 500°C, exhibit exceptional mechanical properties:

• mechanical strength ;

• tenacity ;

• creep resistance ;

• resistance to oxidation and corrosion ;

• structural stability.

There are three families of superalloys:

• nickel-based alloys ;

• iron-nickel base alloys ;

• cobalt-based alloys.

The development of superalloys has been largely based on innovations in alloy chemistry and manufacturing processes. It has mainly been driven by the aerospace and energy industries.

If superalloys have been so successful, it's because they have met the pressing demands of in-service properties. A century ago, generating such power in machines and propulsion systems was scarcely imaginable. Superalloys have helped us conquer air and space, reach the depths of the earth and the ocean, and meet many other challenges of modern life.

As such, they deserve to have their story told, their metallurgy explained and their use illustrated. But it's not an easy task. The evolution of this industry has unfolded through a multitude of small and large events, a multitude of more or less important inventions, at the crossroads of borders, nations and diverse industries. So many people have contributed to the state of the art in 2022, that the light we're going to try to shed on it is bound to be imperfect. But it will be as exhaustive as possible.