Athermal Laser Annealing of Cold-Worked Aluminum

The influence of pulsed laser irradiation on mechanical properties of annealed and cold-worked pure aluminum is studied. Mechanical tests are performed by means of a miniaturized disk bend test technique using specimens with the diameter of 3 mm. It is established that laser irradiation does not influence the mechanical properties of annealed aluminum but leads to softening of cold-worked material. After 100 laser pulses, nearly complete recovery of aluminum strength occurs to the value characteristic of the annealed state. The plasticity of cold-worked aluminum is lower than that of annealed material and does not vary upon laser irradiation. Thermal and shock-wave mechanisms of laser impact are estimated, and it follows that, under the given parameters of irradiation, the main contribution to the variation of properties is that of shock-wave mechanism related to generation and propagation of acoustic waves which stimulate athermal annealing and recovery of dislocation structure.