Local Adiabatic Heating Research Articles

Preparation of Metal Foils by Mechanical Reduction

Annealed and unannealed commercially available beaten foils were used for much of the very early transmission electron microscopy of metals. The studies were restricted to the few highly malleable metals, so, when electropolishing and chemical techniques were developed that permitted many other materials to be thinned as well, beating all but disappeared. It has been found, however, that mechanical reduction techniques provide a simple and rapid means to obtain electron transparent foils of a wide variety of metals and alloys.Tantalum, titanium, platinum, iron, permalloy, silicon-steel, brass, copper, aluminum, cadmium, tin, solder, and lead have all been beaten directly to foil simply by placing a small piece of the material on a polished steel flat and hammering with a steel mallet. The structures observed in the high melting point materials were characterized by high defect densities not unlike those found after explosive loading. Mechanical twins were observed in copper and platinum, and, in many cases structural evidence existed for localized adiabatic heating. Some of the low melting point materials investigated anneal at ambient temperatures and were observed in various stages of polygonization, recrystallization, and grain growth. Electron diffraction revealed a deformation texture in most materials.