Al-Cu-Ce(-Zr) alloys with an exceptional combination of additive processability and mechanical properties

High-temperature Al-9Cu-6Ce and Al-9Cu-6Ce-1Zr (wt%) alloys were designed for fabrication with laser powder bed fusion additive manufacturing (AM). An ultra-fine eutectic structure comprising FCC-Al and particles of a previously unidentified Al8Cu3Ce intermetallic phase was obtained with an inter-particle spacing of approximately 280 nm. The inherent hot-tearing resistance of the eutectic alloys resulted in > 99.5% relative density. A thermodynamic model suggested improved hot-tearing resistance of the present alloys relative to the benchmark AM AlSi10Mg alloy. The Al-Cu-Ce alloy exhibited superior thermal stability with approximately 75% of the asfabricated hardness retained after 200 h exposure at 400 degrees C, owed to the coarsening resistance of the intermetallic particles. The Al-Cu-Ce-Zr alloy age-hardened through precipitation of nanoscale Al3Zr precipitates. The aged microstructure was stable at 350 degrees C with a 13% higher hardness after 200 h exposure compared to the asfabricated condition. The combined influence of ultra-fine spacing and coarsening resistance of the intermetallic particles resulted in the higher yield strength of the Al-Cu-Ce and Al-Cu-Ce-Zr alloys compared to AM AlSi10Mg and Scalmalloy at temperatures greater than 200 degrees C. This work essentially demonstrates that thermally stable Al alloys with exceptional mechanical properties can be produced by additive manufacturing.