Laser beam oscillation welded SiCp/2xx Al alloy: Microstructure, phase interface and mechanical properties

Abstract SiCp/Al matrix composites (SiCp/AMCs), as light and high strength structural alloys, have been widely used in aerospace structural parts, space station solar cell structural framework and other fields. To develop its potential as a structural alloy, SiCp/2 xxxx Al matrix composite plate was selected to investigate its weldability. In this work, the 4 mm thick SiCp/2xx Al joints were prepared via three types laser beam oscillating welding. The formability, microstructure, phase interface and mechanical properties were studied in detail. Results showed that the laser oscillation path significantly affects the formability and tensile properties of the SiCp/2xx Al joint. The tensile strength of the SiCp/2xx Al joint prepared via Clock Wise (CW) oscillation mode reached 192 MPa. The unmelted SiC particles and Al matrix produced a mild ~4 nm Al4C3 transition layer, which had a coherent interface and enhanced the load transfer mechanism. In addition, a formula to quantitatively predict the yield strength of SiCp/Al welded joints was optimized, and the load transfer enhancement mechanism of welded joints was calculated as 14 MPa. It is found that after rapid non-equilibrium solidification, three closely bonded interfaces were characterized, i.e., (200)Al ‖ (104)Al4C3, (103)SiC ‖ (104)Al4C3 and (200)Al ‖ (−511)AlCu. This work provided a process window for laser oscillation mode welding of SiCp/2xx Al matrix composites plate, and also provided a strategy for in-situ construction of transition layer to improve the load transfer mechanism of SiCp/2xx Al welded joint.