Laser powder bed fusion of SiC particle-reinforced pre-alloyed TiB₂/AlSi10Mg composite with high-strength and high-stiffness

Recently, laser powder bed fusion (LPBF) of particle-reinforced aluminum matrix composites (PAMCs) with high-strength and high-stiffness have attracted extensive attention in aviation and aerospace. However, performance improvement of single or dual PAMCs using traditional mechanical mixing method is still limited. Therefore, this study innovatively employed pre-alloyed ∼6.5 wt% TiB₂/AlSi10Mg composite as the matrix and mechanically mixed SiC particles with different contents (5 vol% and 10 vol%) to fabricate dual PAMCs with high particles content through LPBF. The results indicated that the 5 vol% SiC+TiB₂/AlSi10Mg composite revealed relatively weak agglomeration effect of SiC particle and highest relative density (∼99.1 %), thus exhibiting optimal processability. Using this composition material as the research object, it was found that the microstructure maintains the basic features of pre-alloyed TiB₂/AlSi10Mg composite except for the slight grain coarsening. However, SiC particles react with α-Al matrix and Al₃Ti. Then Al₄C₃ and TiC enhancement phase were formed, and micron-sized Si particles precipitated within the Al cells surrounded by the eutectic Al-Si. More importantly, due to novel preparation method of dual PAMCs powder, simultaneous enhancement in ultimate tensile strength (∼554.0 MPa), yield strength (∼376.0 MPa), and elastic modulus (∼97.4 GPa) was achieved. Total particle content (∼14.0 wt%) and tensile property were higher than those of reported other PAMCs processed by LPBF. Finally, expect for the fracture characteristics inherent to the pre-alloyed TiB₂/AlSi10Mg composite, new fracture mechanism for the tearing of SiC particles was exhibited. This work provides new insights into the preparation of high-strength and high-stiffness PAMCs processed by LPBF.