An in-depth understanding of microstructure and resultant properties is paramount in the design of a novel alloy system, especially for additive manufacturing (AM). The present investigation aims to characterize a prototypical AM Al alloy with great potential for structural applications. An Al-1.5Cu-0.8Sc-0.4Zr alloy designed using integrated computational material engineering was printed using the laser powder bed fusion AM process. This novel alloy shows promising combination of strength and ductility in as-built and peak-aged conditions. This improvement in the tensile properties is attributed to the presence of both coherent L1₂ Al₃Sc/Al₃(Sc,Zr) precipitates and Cu-rich regions. The microstructures were studied via extensive microscopy at different length scales using X-ray microscopy, scanning electron microscopy, and transmission electron microscopy. Fractography revealed that the columnar grain boundaries in as-built condition allow easy slip transfer as compared to the equiaxed grains, with the apex of the melt pool acting as the crack nucleation site. However, the peak aged condition resulted in improved strength while marginally sacrificing ductility due to precipitates decorating dislocations, grain boundaries and melt pool boundaries thus acting as obstacles to slip transfer.

在新型合金系统的设计中，尤其是对于增材制造（AM）而言，对微观结构和所得性能的深入了解至关重要。本研究旨在表征具有很大结构潜力的原型AM铝合金。使用激光粉末床熔融AM工艺印刷使用集成计算材料工程设计的Al-1.5Cu-0.8Sc-0.4Zr合金。这种新型合金在制成状态和峰值时效条件下显示出强度和延展性的良好组合。拉伸性能的改善归因于同时存在两种相干的L1 ₂ Al ₃ Sc / Al ₃（Sc，Zr）析出并富铜区域。通过使用X射线显微镜，扫描电子显微镜和透射电子显微镜在不同的长度尺度上通过广泛的显微镜研究了微观结构。断口扫描显示，与等轴晶粒相比，处于等温状态的圆柱状晶界允许容易的滑动转移，而熔池的顶点则作为裂纹的成核位置。但是，峰值时效条件提高了强度，同时由于析出物装饰位错，晶粒边界和熔池边界而略微牺牲了延展性，因此成为滑移传递的障碍。