Benzing, a part of NIST’s Fatigue and Fracture Group in Boulder, Colorado, works on developing and disseminating tools that help quantify the reliability of metallic components that are subjected to a range of forces and loading conditions. He carries out his work with a range of mechanical testing equipment and an electron microscope, his hardworking sidekick. Before we go any further, you should know that, like wood, metal has grains. In fact, the thickness of some of those grains can be smaller than the thickness of a human hair. Our eyes can’t see these grains, obviously, which is where the electron microscope and the EBSD technique come in.
When Benzing applies the EBSD technique to a certain metal, the microscope fires an electron beam into the surface of the sample, which diffracts and creates a pattern on the camera. An EBSD scan—which is a dense dataset of the material’s underlying crystalline structure— contains millions of these patterns and represents the size, shape, and orientation of the grains inside the sample.
Every pixel is assigned a particular color based on the measured pattern, which represents a grain’s orientation and crystalline structure. A metal’s structure will depend on the type of manufacturing process employed, a factor that also plays a role in reliability. Maps can take anywhere from a couple of hours to a few days to produce.