The effect of minor Ti and Mn additions on the microstructure and mechanical properties of additive manufactured Al–Ce–Mg alloys

The Al–Ce-based alloys have gained increasing attentions owing to their favorable properties of high castability and good thermal stability, as well as excellent mechanical performance. However, since Ce has high chemical activity, it tends to bond with other impurities from the raw materials and affect the properties. In the present study, the influence of Ti and Mn impurities on the microstructure and mechanical properties of Al–Ce–Mg alloys was investigated. Both Al–Ce–Mg and Al–Ce–Mg–Ti–Mn alloys exhibit good formability traits during directed energy deposition additive manufacturing. Mechanical testing indicated that Ti and Mn significantly reduce the ductility by forming rosette-shaped Al₂₀Ce(Ti, Mn)₂ ternary intermetallic compounds, which provide favorable sites for the crack initiation in Al–Ce–Mg sample with Ti and Mn impurities. Compared to traditional hot extrusion, the lower solidification rate of direct energy deposition additive manufacturing coarsens the Al₁₁Ce₃ precipitates that compromise the strength but enhance the elongation in the sample without Ti and Mn addition.