An alloy of 1.3% copper, 0.3% magnesium, and 0.3% manganese in aluminum, etched with potassium permanganate and lye.
So I woke up this morning all pumped up to blog about metallography. If you don’t already know, metallography is a type of scientific microimaging that involves mirror-polishing metal surfaces and then etching them with various reagents to reveal their microstructures, which are often of breathtaking beauty.
“Griffith Cannon Flash,” by Dr. Frederick E. Schmidt, from the iron of a cannon used at Gettysburg.
Unfortunately, there aren’t a lot of these images online. ASM International, the big metallurgical professional society, has a large online database of metallographs, but it’s locked away behind a members-only paywall. Except for a couple of skimpy .PDFs (2007, 2008), even the winners of their annual International Metallographic Contest seem to go largely unpublicized.
Which is a shame, not only because the images themselves are so beautiful, but because they could inspire a whole culture of amateur and artistic metallographers that does not, as far as I can tell, presently exist. Which fact also surprises me, by the way, because the equipment and techniques of metallography are very accessible to amateurs, especially relative to other modern methods of materials analysis.
“Grain structure in CC cast 3304 aluminum alloy,” by Elana Naez.
If you know of anyone who’s making metallographs as a hobby or as a means of personal artistic expression, please drop me a link in the comments.