Microstructure and Mechanical Properties of TiC-Reinforced Al–Mg–Sc–Zr Composites Additively Manufactured by Laser Direct Energy Deposition

Abstract

In order to refine the microstructure and improve the performance of direct energy deposited (DED) additively manufactured Al–Mg–Sc–Zr alloy, TiC-modified Al–Mg–Sc–Zr composites were prepared by DED and the effect of TiC content on the microstructure and performance was studied. In the absence of TiC particle, the microstructure of Al–Mg–Sc–Zr alloy prepared by DED consisted of fine grains with average size of 8.36 μm, and well-dispersed nano-Al₃(Sc,Zr) particles inside the grains and Mg₂Si phase along the grain boundaries. With the addition of 1 wt% TiC, the microstructure of TiC/Al–Mg–Sc–Zr prepared by DED became finer apparently compared with that without TiC; while the further increase of TiC content to 3 wt%, the microstructure of TiC/Al–Mg–Sc–Zr prepared by DED became coarser with appearance of a new kind of needle-like (Ti,Zr)₅Si₃ phase. Also, the addition of TiC decreased the porosity of Al–Mg–Sc–Zr prepared by DED. Simultaneously, after the addition of TiC, the tensile strength increased from 283.25 MPa to 344.98–361.51 MPa, and the elongation increased from 3.61% to 9.58–14.10%. The potential mechanism of the microstructure evolution and strength improvement was discussed. This research will provide new insights into the available metal matrix composites by laser additive manufacturing (LAM).