New coating protects steel and superalloys

An electron micrograph of a coated 316 stainless steel coupon in cross-section shows the diffusion-reaction layers. Starting from the left hand side of the photo, which is the surface of the steel the following layers are visible: 1) Aluminum oxide outer layer (not visible at lower magnifications) 2) FeAl layer, 3) Fe₃Al inner layer, and 4) 316SS.