铝基复合材料具有硬度高、切削加工难度大的特点。为了实现高比强度、高比模量铝基复合材料的近净成形，该文利用激光增材制造技术制备了10%（体积分数）微米级SiC颗粒增强AlMgScZr复合材料，建立了激光能量密度、扫描速率与复合材料成形质量的对应关系，通过光学显微镜（OM）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射仪（XRD）和万能试验机对微观组织和力学性能进行表征和测试，探讨了微米级SiC颗粒对选区激光熔化（SLM）成形铝基复合材料凝固组织和力学性能的作用机理。结果表明：在铺粉层厚为30 μm、扫描间距为0.12 mm、激光功率为260 W、扫描速率为1 000 mm/s的工艺参数下，可获得成形质量最佳的SiC/AlMgScZr复合材料，其致密度可达99.81%；激光熔覆过程中，SiC颗粒与Al基体之间发生了剧烈的界面反应，SiC颗粒尖角明显钝化，原位生成的微米级针状Al₄SiC₄条带与残余SiC颗粒形成混合增强结构；时效态SiC/AlMgScZr复合材料的抗拉强度为379 MPa、延伸率为12%、弹性模量为84 GPa，其断裂形式为Al基体的韧性断裂和Al₄SiC₄相的脆性解理断裂，大量交错分布的针状Al₄SiC₄条带是材料发生过早失效断裂的主控因素。

Aluminum matrix composites have the characteristics of high hardness and difficult machining. In order to achieve near-net forming of aluminum matrix composites with high specific strength and high specific modulus, micron SiC particles with volume fraction of 10% reinforced AlMgScZr composites were fabricated using selective laser melting (SLM) technique. The relationship between the laser energy density and scanning rate and the forming quality of the composite was established. The microstructure and mechanical properties were characterized and tested by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and universal testing machine. The effect of micron SiC particles on the solidification structure and mechanical properties of SLMed aluminum matrix composites was investigated. The results show that the best quality composite could be obtained under the conditions of layer thickness of 30 μm, scanning spacing of 0.12 mm, laser power of 260 W, scanning rate of 1 000 mm/s, and its relative density was up to 99.81%. During the laser cladding process, there was a strong interfacial reaction between SiC particles and Al matrix. Micron-sized acicular Al₄SiC₄ bands were formed in situ, and the sharp corners of SiC particles are obviously passivated. Al₄SiC₄ bands and the residual SiC particles formed a mixed reinforced structure. The optimal tensile strength, elongation and elastic modulus of aged SiC/AlMgScZr composites were 379 MPa, 12% and 84 GPa, respectively. The fracture behavior of the composites included ductile fracture of Al matrix and brittle cleavage fracture of Al₄SiC₄ phases. A large number of cross-distributed acicular Al₄SiC₄ bands were the main factors leading to premature failure and fracture of SiC/AlMgScZr composites.