Heat-mass transfer and its effects on the in-situ Al/SiC reactions in aluminum welds during wobbling laser melting injection of SiC particles

The mechanical properties of aluminum welds can be enhanced by the addition of SiC particles via laser melting injection (LMI). During LMI, in-situ reactions will happen in aluminum welds with SiC particles (SiCp) and how to optimize it is challenging. In this paper, a novel process named wobbling laser melting injection (WLMI) is employed to successfully control in-situ reactions of Al/SiC, then improve hardness and wear performance of fusion zone (FZ) on the basis of LMI. Moreover, a multiphase flow model by bidirectionally coupling the computational fluid dynamics and discrete element method (CFD-DEM) is developed to reproduce this process. The temperature and velocity fields of both Al fluid and SiCp during WLMI are characterized by numerical simulation. Firstly, the area greater than 1670 K can go through all parts of molten pool under WLMI compared with LMI that area just stays in the melt middle. Secondly, the temperature of particles prepared with WLMI can reach 1670 K and the duration above 940 K is longer. These special kinetic-thermodynamic behaviors during WLMI will cause in-situ products Al4SiC4 to be distributed evenly in Al substrate, and on SiC/Al interface. Finally, the evenly distributed strengthening phase in Al matrix and the strong bonding force of SiC/Al interface under WLMI result in better microhardness and wear performance of FZ respectively compared with LMI.