Microstructure and properties of SiCp/2009 Al MMCs welded joint of laser filler wire welding with preset gap

The oscillating laser wire filling welding process was employed to achieve butt welding of SiCp/2009 Al MMCs with a 1.3 mm preset gap. The influence of wire feeding speed on weld formation was investigated, and the microstructural evolution, mechanical properties, and fracture characteristics of welded joints under optimal wire filling conditions were systematically analyzed. Results indicate that with other welding parameters held constant, appropriate wire feeding speed enables effective filling of the preset gap, while insufficient or excessive speeds both lead to deteriorated weld formation. The microstructure of welded joints exhibited heterogeneity. Compared with the base material, the heat affected zone showed reduced Al₂Cu particle size but increased quantity due to thermal cycling effects, while only limited SiC and Al₂Cu particles remained in the weld zone. The decreased base material dilution rate and enhanced laser energy utilization for melting ER5356 filler wire collectively reduced SiC dissolution, effectively inhibiting Al₄C₃ formation. Tensile tests revealed that the joint strength reached 68.9% of the base material, with brittle fractures occurring near the fusion line. The primary failure mechanism was attributed to defects resembling void that reduced effective load-bearing cross-sectional areas at these locations.