TiC addition enhances thermal stability and mitigates intermediate-temperature embrittlement in Al–Ce–Ni additively manufactured via laser powder bed fusion

Al–Ce-based alloys processed using laser powder bed fusion (LPBF) are characterized by a high-volume fraction of eutectic networks. While exhibiting promising elevated temperature (250–400 °C) mechanical properties, they suffer from strength degradation after prolonged thermal exposure and a decrease in elongation-to-fracture (ε_f) with increasing temperature. Here, we show that adding 5 wt.% TiC particles to a near-eutectic Al–10Ce–4Ni (wt.%) (AlCeNi) alloy mitigates both issues, albeit at the expense of reduced room-temperature ε_f . TiC addition reduces solute supersaturation in the α-Al matrix, increases the volume fraction of intermetallics, and promotes a more homogeneous melt-pool-scale microstructure. It also enhances thermal stability, as evidenced by a higher hardness retention ratio after thermal exposure, due to the suppressed coarsening of intergranular Ni-rich phases and the formation of a stable Al₂₀Ti₂Ce phase. AlCeNi exhibits an ε_f dip over 250–350 °C, caused by aggravated void nucleation and growth in the relatively softer heat-affected zone (HAZ), even with an increased strain rate sensitivity (SRS). TiC addition induces melt-pool-scale homogeneity and a TiC–matrix heterogeneity, shifting strain localization from HAZ to TiC particles. The failure evolves from TiC particle cracking (RT–200 °C) to void nucleation (300–400 °C), enabling more progressive damage evolution. This weakens the heterogeneity-induced reduction in ε_f under the increased SRS at RT–350 °C, thereby eliminating the ε_f dip. These findings identify TiC-assisted composition control as an effective route to simultaneously enhance thermal stability and suppress ε_f dip in LPBF near-eutectic Al alloys for high temperature service. © 2026 Acta Materialia Inc.