As high-speed aircraft, aerospace engines and other advanced equipment are developing towards lightweight, complex structures and higher heat resistance, additive manufacturing (AM) heat-resistant aluminum (Al) alloys that can operate at 200–400 °C are receiving significant attention. However, traditional heat-resistant Al alloys are not suitable for AM, so the research on AM-specific heat-resistant Al alloys is currently a new research hotspot, and related processes, materials and mechanism studies are constantly emerging. This paper provides a comprehensive review of the most recent advancements in the AM heat-resistant Al alloys. Firstly, the development status and high temperature mechanical properties of heat-resistant Al alloys in different series were reviewed, especially the novel systems such as Al-Ni, Al-Fe and Al-Ce, which exhibit excellent performance in proper composition (≥100 MPa at 400 °C). Secondly, on the basis of the reported literature, this paper comprehensively discusses the general heat resistance mechanisms and outlines a series of theories for improving thermal stability, including multi-component synergistic effect and atomic-scale segregation strengthening. Finally, the future research is prospected, with the hope that this work will serve as a valuable reference for the ongoing development of heat-resistant Al alloys.

Selective laser melting (SLM) and direct energy deposition (DED) are two widely used technologies in additive manufacturing (AM). However, there are few studies on the combination of the two technologies, which can synthetically combine the advantages of the two technologies for more flexible material design. This paper systematically studies the Al-Mg-Sc-Zr alloy by combination of SLM and DED with emphasis on its bonding properties, microstructure, and metallurgical defects. It is found that the aluminum alloy prepared by the two methods achieves a good metallurgical combination. The microstructure of aluminum alloy prepared by DED is composed of equiaxed crystals, and there are a large number of Al₃(Sc, Zr) precipitated phase particles rich in Sc and Zr. The microstructure of SLM aluminum alloy is composed of equiaxed crystals and columnar crystals, and there is a fine-grained area at the boundary of the molten pool. With the decrease of laser volumetric energy density (VED), the width and depth of the molten pool at the interface junction gradually decrease. The porosity gradually increases with the decrease of VED, and the microhardness shows a downward trend. Tensile strength and elongation at fracture of the SLM printed sample at 133.3 J/mm³ are about 400 MPa and 9.4%, while the direct energy depositioned sample are about 280 MPa and 5.9%. Due to the excellent bonding performance, this research has certain guiding significance for SLM–DED composite aluminum alloy.