Inconel

Inconels are a class of nickel-chrome-based super alloys characterized by high corrosion resistance, oxidation resistance, strength at high temperatures, and creep resistance. Inconel is able to withstand elevated temperatures and extremely corrosive environments due to two factors. One reason is because of the formation of the intermetallic compound Ni3Nb in the gamma double prime (ɣ’’) phase. This intermetallic phase acts as a ‘glue’ on the grain boundaries. This ‘glue’ prevents the grains from increasing in size when heated to high temperatures. Second, Inconel has a high corrosion resistance due to the passivation layer that forms when heated. Both of these factors make Inconel ideal alloys for applications from hot section gas turbines to deep sea well drilling. So what is the downside of these alloys? They are expensive, hard to machine, and hard to work.