Microstructure and mechanical characterization of Nd:YAG laser beam welded AA6061/10 wt% ZrB₂ aluminum matrix composites

Laser beam welding (LBW) of AA6061/10 wt% ZrB₂ aluminum matrix composites (AMCs) demonstrated substantial benefits compared to other welding processes. In this research work, 4 mm thick AA6061/10 wt% ZrB₂ composite plate was effectively joined using Nd:YAG LBW. The welding was carried out using varied scanning speed in the range of 1.7–2.5 m/min by keeping a constant laser power. The role of scanning speed on the fusion zone microstructure was studied using X-ray diffraction analysis (XRD), conventional and advanced microscopic techniques to find out the transformation in the morphology and the thermodynamic stability of ZrB₂ reinforcement particles. XRD and microstructural results showed partial disintegration of ZrB₂ particles in the fusion zone to form Al₃Zr compound. The increase in scanning speed reduced the formation of Al₃Zr compound. The grain size in the fusion reduced remarkably with an increase in the scanning speed. The dislocation density also increased in the fusion zone due to the rapid solidification process. The microstructural change in the fusion zone enhanced the microhardness and the details of tensile strength were further presented.