Researchers have demonstrated the ability to create amorphous metal (metallic glass) alloys on large scales using 3D printing technology. Metallic glasses lack the crystalline structures of most metals, so the amorphous structure results in exceptionally desirable properties.
Unfortunately, making metallic glass requires rapid cooling to prevent the crystalline structure from forming. Historically, that meant metallic glasses could only be cast into small thicknesses; for example, amorphous iron alloys could be cast no more than a few millimeters thick. That size limitation is called an alloy's critical casting thickness. Using additive manufacturing, or 3D printing, enabled production of an amorphous iron alloy on a scale 15 times larger than its critical casting thickness.
The technique works by applying a laser to a layer of metal powder, melting the powder into a solid layer that is only 20 microns thick. The “build platform” then descends 20 microns, more powder is spread onto the surface, and the process repeats itself. Because the alloy is formed a layer at a time, it cools quickly, retaining its amorphous qualities. The end result is a solid, metallic glass object — not an object made of laminated, discrete layers of the alloy.