In-service oxidation and microstructural evolution of a nickel superalloy in a formula 1 car exhaust

The oxidation response and microstructural evolution of an Inconel 625 alloy exhaust manifold exposed to an automobile racing environment has been examined using a range of advanced electron microscopy-based techniques, atom probe tomography and high sensitivity laser ablation mass spectrometry. The dynamic, corrosive gas conditions result in accelerated oxidation, with the inner exhaust surface also heavily contaminated by multiple species including Zn, P, K and Na. Nb carbides and Ti nitrides identified in stock control samples evolve into mixed (Ti,Nb)N species during exposure, decorated by smaller Mo, Si-rich precipitates. The exposed alloy component therefore reveals unique surface and sub-surface features following in-service use