Developing Blast-Resistant Steel Using New Tomograph

Northwestern University materials scientists and engineers are developing a new “high-security” steel that would be resistant to bomb blasts. The researchers now have a state-of-the-art instrument that enables them to get a precise look at steel’s composition on the nanoscale: a $2 million atom-probe tomograph that is only the fourth of its kind in the world.

Using the new Local-Electrode Atom-Probe (LEAP®) tomograph, researchers studying steel and other materials can — at amazing speed — pluck atoms off a material’s surface one at a time, layer by layer over tens of thousands of layers, to better understand the entire nanostructure and chemical composition of the material, which is key to designing new materials effectively and efficiently.

The technology is similar to that used in CT (computed tomography) scans, which image body tissues for medical diagnosis. Consisting of a field-ion microscope plus a special time-of-flight mass spectrometer, an atom-probe tomograph takes multiple pictures and uses those slices to construct a detailed three-dimensional image of the material.

The LEAP tomograph has a very large field of view, analyzes significantly larger volumes of material, and collects data more than 720 times faster than its predecessor at Northwestern, a conventional 3D Atom-Probe tomograph. The LEAP tomograph collects 72 million atoms per hour while the old tomograph collects merely 100,000 atoms in the same amount of time. The specimen is held in the tomograph at cryogenic temperatures, immobilizing the nanostructure so that when atoms are removed, the remaining structure is not affected. Each atom’s position and chemical identity are recorded, and the data are then used to create a 3D image of the material’s complex atomic structure.

Find out more at: http://arc.nucapt.northwestern.edu/Seidman_Group