Effect of UV laser irradiation on the hardness and structural parameters of AgxPd1−x (0.4 ≤ x ≤ 0.6) alloys

Strips of high-purity AgxPd1−x alloys, with x = 0.4, 0.5 and 0.6, were solution treated at 800 °C for 2 h. Specimens of each composition were then irradiated with 100, 200, 300, and 400 shots of KrF Excimer laser (maximum energy 20 mJ, wavelength 248 nm, pulse width 20 ns, repetition rate 20 Hz). For each alloy, Vickers hardness of un-irradiated and irradiated specimens was measured as a function of the number of laser shots, and was found to increase with increasing number of shots. The increase in surface hardness at the midpoint of laser irradiation spot on Ag40Pd60, Ag50Pd50, and Ag60Pd40 specimens was up to 27.6, 30.2, and 17.3%, respectively. The surface hardness profile for each irradiated specimen shows a decreasing trend till a distance of 3 mm from the midpoint of the irradiated spot. XRD study of the alloy specimens of each composition shows that the dislocation line density increases with increasing number of shots, and the surface hardness is a function of it.