Characterizing Laser-Modified Microstructures and Electrical and Mechanical Properties of Al-15.3%Si(wt.%) Alloys

Characterization of metallic alloys is of significant interest for fundamental and practical prospects. In this manuscript, we report on the laser-ablation-modified electrical and mechanical properties of Al-15.3%Si(wt.%) alloys correlated with the grain refinement and micro/nanostructuring subjected to various KrF excimer laser pulses. Herein, the irradiation was performed in air at atmospheric pressure by varying laser pulses ranging from 100 to 500. For different laser pulses, the variation in the peak intensities, crystallite sizes, and dislocation line densities were investigated by using XRD techniques. The maximum decrease in grain size (21.21 nm) at 300 laser pulses and maximum increase in grain size (31.6 nm) at 500 laser pulses is observed. Surface morphological changes reveal that irradiated targets are modified by craters, cones, and molten, redeposit material in the form of ripples. Hydrodynamic sputtering, splashing, and exfoliation are the dominant ablation mechanisms. Non-uniform heat conduction takes place on the surfaces in the form of laser-induced cellular or columnar surface structures at maximum pulses. Four-Point Probe revealed that electrical resistivity increases firstly up to 300 laser pulses but at 500 pulses, an abrupt decrease in electrical resistivity is observed. The hardness was tested in three different zones, and it was discovered that the highest hardness was present in all samples of the heat-affected zone. The un-irradiated sample had a hardness value of 91.4 HV, which increased to 127.6 HV when the intensity of laser pulses was raised to 300. Irradiated samples with 400 and 500 laser pulses had lower hardness and dislocation defect density, which was attributed to irradiation-induced annealing. The results are believed to be beneficial in the surface engineering of materials for practical applications such as the electronics, automobile, and aerospace industries. Particularly, they are more important in the automotive body structuring and aviation sector because of their excellent role in providing fuel saving and preventing spare parts from corrosion resistance.