Wright brothers' aircraft engine precipitate coarsening (Smithsonian study)

Brief teaching aside on natural aging. SEM study of the engine block in the Smithsonian showed aluminum-copper precipitates still coarsening after a hundred years at room temperature; data fell on a straight line on a log-time scale.

They once did a study of the Wright brothers' engine, the one in the Smithsonian. Someone took a little sample off, ran it under the scanning electron microscope, and looked at how the aluminum-copper precipitates had grown over a hundred years. They put it on a log-scale graph, and those things are still precipitating at room temperature sitting in the Smithsonian. Everything falls on a straight line. They're getting coarser over time.