Pulsed ion-beam processing of materials: Opportunities from the materials view

Summary form only given. The authors discuss some of the opportunities and requirements for pulsed ion-beam processing from a materials view. The current understanding of rapid phase transformations in the 100-ns time regime is reviewed based on early pulsed laser processing research. Quench rates required for glass formation in metallic alloys, limits to supersaturation of impurities in alloys, and formation of unique microstructures are discussed. While ion beams operate in the time regime of laser sources, the energy deposition is volume rather than surface dominated, and is essentially independent of surface condition. These differences eliminate surface instabilities inherent in laser processing, but raise potentially new difficulties with subsurface melting and thermal stresses. The use of alternate beams and/or shaped voltage pulses to control the energy deposition is also discussed. Preliminary experiments to measure properties of pulsed ion treated materials have been performed. For simple ferrous alloys, surface roughness, thermal stress, and hardness were studied as a function of incident ion energy density.