Additive manufacturing (AM) by electron beam melting (EBM) has many advantages over the laser-based AM techniques, but is subjected to a lower cooling rate and a long time thermal exposure with a much higher temperature. Therefore, the EBMed aluminum alloys commonly have coarser solidification structures such that lower mechanical properties compared to their SLMed counterparts. In this work, we proposed a strategy of introducing TiB₂ particles into heat-resistant Al-Cu-Mg-Fe-Ni alloy to enhance the grain refinement and heat resistance for EBM fabrication. Applying a “presintering-densification” scanning strategy, near fully dense samples were build up with precise contours and good surface quality. The as-built EBMed TiB₂/Al-Cu-Mg-Fe-Ni composite possessed a highly homogeneous microstructure with uniformly distributed TiB₂ and Fe/Ni rich intermetallic particles. A fully equiaxed grain structure was achieved in the composite with a profoundly refined grain size of ~9 µm. The improved grain refinement effect was attributed to the sufficient activation of TiB₂ particles as heterogeneous nuclei under a high cooling rate. Additionally, the solidified microstructure has shown an excellent thermal stability under ~500 °C during EBM process. The coexistence of thermal stable TiB₂ and Fe, Ni-rich intermetallics at grain boundaries restricted the grain growth effectively. The as-built composite exhibited a high tensile strength of 253.4 MPa with an outstanding elongation of 13.5%. After a T6-like heat treatment, the tensile strength was increased to 322 MPa with an elongation of 9.8%. This study might shed a new light on designing high performance aluminum alloys/composites suitable for EBM technique.

与基于激光的增材制造技术相比，通过电子束熔化 (EBM) 制造的增材制造 (AM) 具有许多优势，但其冷却速度较低，并且需要长时间的热暴露和更高的温度。因此，EBMed 铝合金通常具有较粗的凝固结构，因此与 SLMed 对应的铝合金相比，其机械性能较低。在这项工作中，我们提出了一种将 TiB ₂颗粒引入耐热 Al-Cu-Mg-Fe-Ni 合金的策略，以提高 EBM 制造的晶粒细化和耐热性。应用“预烧结致密化”扫描策略，建立了接近完全致密的样品，具有精确的轮廓和良好的表面质量。竣工的 EBMed TiB ₂/Al-Cu-Mg-Fe-Ni复合材料具有高度均匀的微观结构，具有均匀分布的TiB ₂和富含Fe/Ni的金属间化合物颗粒。在复合材料中实现了完全等轴的晶粒结构，晶粒尺寸非常细化，约为 9  µm。改善的晶粒细化效果归因于在高冷却速率下作为异质核的TiB _{2颗粒的充分活化。}此外，在 EBM 工艺期间，凝固的微观结构在约 500 °C 下表现出出色的热稳定性。晶界处热稳定的TiB ₂和富Fe、Ni金属间化合物的共存有效地限制了晶粒的生长。竣工后的复合材料具有 253.4 的高抗拉强度 MPa，伸长率为 13.5%。经过类 T6 热处理后，抗拉强度提高到 322  MPa，伸长率为 9.8%。这项研究可能为设计适用于 EBM 技术的高性能铝合金/复合材料提供新的思路。