Bulk nanocrystalline steel

Most new materials are introduced by selectively comparing their properties against those of steels. Steels set this standard because iron and its alloys have so much potential that new concepts are discovered and implemented with notorious regularity. In this 52nd Hatfield Memorial Lecture, a remarkably beautiful microstructure consisting of slender crystals of ferrite, whose controlling scale compares well with that of carbon nanotubes, is described. The crystals are generated by the partial transformation of austenite, resulting in an extraordinary combination of strength, hardness and toughness. All this in bulk steel without the use of expensive alloying elements. We now have a strong alloy of iron, which can be used for making items that are large in all three dimensions, which can be made without the need for mechanical processing or rapid cooling and which is cheap to produce and apply.