Tunable TiAl3-reinforced aluminum matrix composites via in-situ reactive printing: insights from operando synchrotron analysis and microstructural characterization

Additive-manufactured TiAl3-reinforced aluminum matrix composite (AMC) materials were fabricated by forming TiAl3 whiskers from an in-situ reaction in laser direct energy deposition (L-DED) between aluminum (Al) and titanium (Ti). The composite demonstrates enhancements in mechanical strength with tunability compared to the unreinforced material, while using feedstock mixtures of commercially available Al and Ti powder with standard size distributions. This enhancement in mechanical strength is attributed to load transfer from the strong TiAl3 reinforcement and the Hall-Petch strengthening from the refined grain size of the Al matrix. Operando synchrotron analysis of the solidification sequence in laser powder bed fusion (L-PBF) of the Al-Ti material system, coupled with postmortem microstructural characterizations, reveals that the dispersed TiAl3 whiskers refine Al grain size by promoting heterogeneous nucleation through in-situ inoculation. This study validates the methodology of forming reinforcement phases from in-situ reactions to enable the fabrication of enhanced, tunable AMC via L-DED or L-PBF.