Influence of Pulse Energy and a Material’s Magnetic Field on the Morphology of the Dimples Produced with Nanosecond Pulsed Laser on a Magnet

Magnets made of NdFeB alloys are applied in numerous industries because they have excellent magnetic properties and good thermal stability. However, their low corrosion resistance and fragility reduce the number of the applications in harsh environments. Laser surface texturing is a powerful technique to improve the properties of materials via surface functionalisation. The characteristics of the textures define the properties of the functionalised surfaces and the laser parameters in turn influence the texture features. Pulse energy is a laser parameter with high influence on the geometry and the morphology of the textures. The magnetic field of these magnets are also expected to have an influence on the texture features. In this present work, the influence of the pulse energy (from 5µJ to 696µJ) on the dimple characteristics created with an infrared (1064 nm) nanosecond pulsed (200ns) fibre laser single pulses on NdFeB alloy (magnetic material) have been studied. The shape features of the laser textures on the samples were analysed through optical microscopy and profilometry. This work shows that the single pulses produced textures of U-type dimple kind on the metallic material. The shapes of the dimples were also altered by magnetic field of the material, which indicates that the magnetic properties of the alloys remain in liquid state. The factors of the laser beam-material interaction, pulse energy and energy depth penetration, are furthermore presented in this paper. These factors can be employed to design the width, diameter and depth of the dimples.