Stress waves generated by a giant pulsed laser were used to change the in-depth microstructural and mechanical properties of 7075 aluminum. The 0.2% offset yield strengths of 7075-T73 and unaged 7075 aluminum were increased as much as 30% over unshocked values. Microstructural analyses showed that laser shocking induced a tangled dislocation substructure similar to explosively shocked aluminum.
Stress-wave environments generated at a confined surface by a pulsed laser were investigated.Experimental measurements and theoretical calculations demonstrated that confinement of the surface with a transparent overlay provided an effective method of generating high-amplitude laser-induced stress waves in the target material. Peak pressures approaching 10 GPa were possible at laser power densities of several times 10 9 W/cm 2 for laser pulse durations ranging from several nanoseconds to several tens of nanoseconds. These pressures were generated in an air environment at standard conditions, thus enhancing their practical utilization for processing of materials and measurements of material properties. At laser power densities greater than 10 9 W/cm 2 , the laser-induced stress-wave environment was controlled by properties of the ionized plasma created near the metal surface. Some enhancement in the amplitude and duration of laserinduced stress-wave environments was observed at laser power densities less than 10 9 W/cm 2 if low thermal conductivity and low heat of vaporization materials were used. Calculations show that peak pressures greater than 10 GPa were possible by superimposing stress waves either through reflection off a high acoustic impedance barrier or through the interaction of stress waves which were generated at different surfaces of a material.
Laser-induced stress waves in iron samples were analyzed by measuring the pressure environment at the back surface of various sample thicknesses. These results were compared with numerical calculations obtained from a one-dimensional radiation hydrodynamics computer code. The experiments were conducted in an air environment under ambient conditions and the metal surfaces were confined by transparent overlays. Peak pressures exceeding 50 kbar were measured with quartz pressure transducers at a laser power density of about 109 W/cm2. Computer predictions agreed favorably with the experimental results and indicated that peak pressures exceeding 100 kbar could be generated by appropriate modifications in the laser environment and target overlay configuration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.