The pre-alloyed TiB₂/AlSi10Mg composite, a new high-strength aluminum alloy developed for laser powder bed fusion (LPBF) technology, offers promising applications in lightweight and multi-scaled structures. However, thermal behavior during LPBF is markedly scale-dependent, leading to microstructural variations that significantly affect the load-bearing capacity of multi-scaled structures. Therefore, this study systematically investigates the scale-dependent behavior of microstructure characteristics of this composite. Utilizing a hatching scanning strategy, it was found that the marginal zones of samples are predominantly composed of coarse Al cell and Al grain structures, contrasting with the fine microstructures in the central zones. With increasing structure scale, cell and grain structures in both the marginal and central zones become more refined, with cell sizes reducing by 49%–72% (∼3.02 μm → 0.86–1.55 μm). Particularly, the minimum-scaled structures also feature broken eutectic Si particles and nanopores. The essence is primarily due to the low heat dissipation with higher peak temperature and longer duration time at high temperatures in both the small-scale structures and marginal zones. Additionally, smaller structures correlate with reduced microhardness and tensile strength, accompanied by the “softening” of the marginal zones. The strength of the minimum-scaled structure is only half that of the standard sample. Our findings suggest a scale threshold of 2.0 mm for researching scale effect. Encouragingly, incorporating additional contour scanning significantly counteracts the adverse influence of the scale effect. Owing to the combined influence of extended inter-layer time and laser remelting, all samples demonstrate a distinctly refined microstructure. This results in consistently high levels of microhardness and strength, with the “hardening” of the marginal zones. Eventually, the relationship between mechanical properties and microstructure sizes is established. This study provides valuable insights into the innovative designs and engineering applications of multi-scaled structures in LPBF using various materials.

预合金 TiB ₂ /AlSi10Mg 复合材料是一种专为激光粉末床熔合 (LPBF) 技术开发的新型高强度铝合金，在轻质和多尺度结构中具有广阔的应用前景。然而，LPBF 期间的热行为明显依赖于尺度，导致显微结构变化，从而显着影响多尺度结构的承载能力。因此，本研究系统地研究了该复合材料微观结构特征的尺度相关行为。利用孵化扫描策略，发现样品的边缘区域主要由粗大的铝细胞和铝晶粒结构组成，与中心区域的精细微观结构形成鲜明对比。随着结构尺度的增加，边缘和中心区域的细胞和晶粒结构变得更加细化，细胞尺寸减小了49%–72%（∼3.02 μm → 0.86–1.55 μm）。特别是，最小尺度的结构还具有破碎的共晶硅颗粒和纳米孔。其本质主要是由于小尺度结构和边缘区域的散热能力较低，峰值温度较高，高温持续时间较长。此外，较小的结构与显微硬度和拉伸强度降低相关，并伴有边缘区域的“软化”。最小尺寸结构的强度只有标准样品的一半。我们的研究结果表明，研究尺度效应的尺度阈值为 2.0 毫米。令人鼓舞的是，结合额外的轮廓扫描可以显着抵消尺度效应的不利影响。 由于延长的层间时间和激光重熔的综合影响，所有样品都表现出明显细化的微观结构。这导致了持续高水平的显微硬度和强度，以及边缘区域的“硬化”。最终，建立了机械性能和微观结构尺寸之间的关系。这项研究为使用各种材料的 LPBF 多尺度结构的创新设计和工程应用提供了宝贵的见解。