High-Stiffness Aluminum Matrix Composites Reinforced with (Zrc+Tic) Ceramics by Laser Powder Bed Fusion

The fraction of in-situ synthesized reinforcements significantly affects the properties of composites, which is closely correlated to the constituent content incorporated into the composites. In this work, (ZrC+TiC)/Al composites with different (ZrC+TiC) ceramic contents (10, 15, and 20 wt.%) are fabricated by laser powder bed fusion (LPBF). The influence of the (ZrC+TiC) ceramic content on laser absorptivity, formation and fraction of in-situ formed reinforcements, micro/nano hardness and elastic modulus of the LPBF-fabricated (ZrC+TiC)/Al composites is investigated . The effect of ceramic content on the strengthening efficiency of the composites is revealed. In the LPBF process, ZrC ceramic particles react in-situ reacts with TiC, and (Ti,Zr)C nano-particles precipitate. When the (ZrC+TiC) content increases from 10 to 20 wt.%, the laser absorptivity, the reaction product fraction and the micro/nano hardness of the (ZrC+TiC)/Al composites increase, reaching a high microhardness of 120±10 HV 0.2 and a nano hardness of 1.33±0.18 GPa. The 15 wt.% (ZrC+TiC)/Al composites show a higher elastic modulus of 94.4±7.4 GPa and tensile strength of 280 MPa than the unreinforced Al matrix (~70 GPa and 82 MPa), which is ascribed to the combined effects of coherent reinforcement/matrix interfaces for effective load transfer and formation of (Ti,Zr)C nano-precipitates.