ORIGINAL ARTICLE M. Z. Butt 1 & Ammal Javed 1 & M. Waqas Khaliq 1 & Dilawar Ali 2 & Farooq Bashir 3 Received: 8 June 2016 /Accepted: 25 September 2016 /Published online: 3 October 2016 # Springer-Verlag London 2016 Abstract Specimens of Pd 80 Ni 20 alloy were irradiated in air with 70, 80, 90, and 100 laser shots using a Q- switched Nd-YAG laser of 1064 nm wavelength with pulse duration 10 ns, energy 50 mJ, and repetition rate 10 Hz. Surface morphology of the laser-irradiated speci- mens was studied with the help of a scanning electron microscope. It includes wave-like structures or ripples, dips, ridges, microcones, flakes, and fissures, etc. The X-ray diffraction patterns of un-irradiated and irradiated specimens were analyzed using the Williamson–Hall method to evaluate crystallite size and microstrain. Texture coefficient was determined by Harris analysis. The peak intensity of (111), (200), (220), (311), and (222) planes increases linearly with laser shots, which shows that the concentration of point defects (i.e., vacancies) is progressively decreased on increasing the number of laser shots due to the annealing processes. Surface hardness was measured using a Vickers hardness tester. The average surface hardness of the specimens ini- tially decreases on irradiation with 70 laser shots and later on increases linearly with increase in laser shots up to 100. An inverse Hall-Petch relationship is observed in the crystallite size range 19–27 nm. As crystallite size decreases from 27 to 19 nm, volume fraction of amor- phous phase increases progressively. The amorphous phase being softer than crystalline phase due to increased atomic spacing leads to reduction in surface hardness of the material. Keywords Pd 80 Ni 20 alloy . Nd–YAG laser . Structural analysis . Surface morphology . Hardness . PACS 61.05. Cp . 61.80. Ba . 61.82. By . 81.40. Wx . 81.70. Bt 1 Introduction Palladium is an important catalytic metal used for diverse applications ranging from emission reduction in wood log stoves and biomass combustion systems for pollution-free environment [1–4] to switchable mirrors, hydrogen sen- sors, hydrogen storable materials, smart windows, and energy-saving materials [5–7]. As far as switchable mir- rors are concerned, the optical properties of these can change between mirror and transparent states by alternate exposure to diluted hydrogen and oxygen. Yoshimura et al. [ 5] have reported that Pd-capped Mg–Ni alloy thin-film switchable mirrors exhibit excellent optical switching properties as well as fast hydrogen absorption and desorption kinetics. However, the high cost of Pd layer hampers its practical applications. Zhang et al. [6], Highlights for Review • Pd 80 Ni 20 specimens were irradiated with 70, 80, 90, and100 infrared laser shots • Texture coefficient of Pd 80 Ni 20 alloy depends on the number of laser shots • Surface roughness decreases from 2.8 to 0.9 μm with the increase in laser shots • Surface hardness increases from 165 to193 HV with the increase in laser shots • Inverse Hall–Petch relation is observed in the crystallite size range 19– 27 nm * M. Z. Butt mzakriabutt@gmail.com 1 Centre for Advanced Studies in Physics, GC University, Lahore 54000, Pakistan 2 Department of Physics, GC University, Lahore 54000, Pakistan 3 Central Research Laboratory, LCW University, Lahore 54000, Pakistan Int J Adv Manuf Technol (2017) 90:1857–1869 DOI 10.1007/s00170-016-9526-z Impact of 1064 nm–10 ns pulsed laser on the surface morphology, structure, and hardness of Pd 80 Ni 20 alloy