Better Understanding of How Metallic Glass Fails
Typically crystals are thought of as being beautiful stones used in jewelry, but many more materials are crystals, including metals. As molten metal cools, its atoms will align into a structure that gives it certain properties, but it is possible to force the atoms to not align properly, producing a metallic glass. Due to the amorphous structure, metallic glasses can have special properties, including great ductility, and researchers at Los Alamos National Laboratory, the University of Wisconsin, Madison, Universitat de Barcelona, and Tohoku University are working to improve those properties.
Unlike the glass of a window pane, metallic glasses can be quite flexible, but they will still reach a point where they fracture. Instead of fracturing, the researchers want the metallic glass to fail like other, more ductile materials. To learn how to do that the researchers examined shear bands, which form in a material to relieve the stress applied to it, using nanoindentation. The idea behind nanoindentation is simple enough, as it involves pressing a needle into the material, with all of the force concentrated at the tiny tip. The researchers did this repeatedly to find where and when the shear bands formed.
By controlling the formation of shear bands, it should be possible to control how a metallic glass will fail, and thus a way to shape the material's properties. The researchers have already found that there are multiple types of initiation sites for shear bands, which is counter to the assumption that only one exists.
Source: Los Alamos National Laboratory