Most metals — from the steel used to build bridges and skyscrapers to the copper and gold used to form wires in microchips — are made of crystals: orderly arrays of molecules forming a perfectly repeating pattern. In many cases, including the examples above, the material is made of tiny crystals packed closely together, rather than one large crystal. Indeed, for many purposes, making the crystals as small as possible provides significant advantages in performance, but such materials are often unstable: The crystals tend to merge and grow larger if subjected to heat or stress. Now, MIT researchers have found a way to avoid that problem. They’ve designed and made alloys that form extremely tiny grains — called nanocrystals — that are only a few billionths of a meter across. These alloys retain their nanocrystalline structure even in the face of high heat. Read more on MITnews.
Chookajorn and Murdoch on Stable Nanocrystalline Metals
September 4, 2012