Amorphous metals? Most people are aware that metals have a crystalline structure. If you take a piece of wire like a paperclip and bend it back and forth, you increase the size of these crystals through a process called cold-working and it will soon break along these crystal boundaries. Given a large enough piece being bent until it breaks, these crystals can be easy to see. Amorphous metals are sometimes called metal glasses because they show the same sort of non-crystalline structures that glass shows. (amorphous means "without shape")
cool molten metals at extreme rates. The first experiments chilled the metals at a trillion degrees Kelvin per second. That's a hard number to grasp, so for example this would be equivalent to cooling molten Nickel at 2913C (3186K) to liquid nitrogen temperatures of 70K in 3.1 nanoseconds. Only very thin layers (< 50 µm) could possibly transfer heat that fast. Work since then has focused on coming up with alloys that can be cooled at lower rates, by using metals with extremely different atomic sizes and current numbers for cooling rates are in the range of 1000 K/s and under. Rates down to 1 K/s have been shown. This allows much more useful sizes.
OK, cooling something at a trillion degrees per second is a pretty outrageous achievement, but even 1000 degrees K/sec in a 3D printer sounds extremely difficult. Why do it? Heraeus sums it up in this statement:
“Amorphous metals will change our future. They possess a wide variety of previously incompatible characteristics: They are very strong and yet malleable, as well as harder and more corrosion-resistant than conventional metals...”Continuing from their press release announcement:
Amorphous metals are suitable for an exceptional number of high-tech applications. They are energy-absorbing and scratch-proof while still having very good spring characteristics – interesting for injection nozzle diaphragms, casing for consumer electronics, or as dome tweeters for speakers. “For fifty years the commercial success of amorphous metals has been held back by inadequate manufacturing methods. Now that changes. Exmet looks forward to cooperating with Heraeus as a competent partner with a worldwide network to help bring this disruptive new technology to the market,” says Mattias Unosson, Exmet co-founder and CEO.While this was exotic technology when I was in school, today, metal glasses are manufactured in quantity for some specialized applications. Still, a way to produce them using additive manufacturing appears to be able to open up new applications and new markets for amorphous metals. It's a shame Heraeus doesn't feel fit to give us even a clue how they do it. Their release describes what sounds like conventional laser or electron beam sintering of metal powders. I know it's proprietary, but it would be fun if they mentioned they sintered a spot and then sprayed a drop of liquid nitrogen on it!