利用粉末热挤压工艺制备 SiCp/2024铝基复合材料，研究所制备复合材料的挤压态和热处理态的显微组织及力学性能，分析复合材料的断口形貌和断裂类型。结果表明：大部分SiC颗粒和析出的大量细小第二相粒子均匀地分布在基体合金中，部分区域的SiC颗粒存在轻微团聚现象，晶粒沿挤压方向被显著拉长，刚性的SiC颗粒长轴平行于挤压方向分布，形成热加工纤维组织。对复合材料进行T6(490℃固溶75 min+170℃时效8 h)热处理后，复合材料的晶粒比较细小，抗拉强度达470 MPa，主要的析出强化相为S′(Al2CuMg)。挤压比的提高有利于提高SiC颗粒和基体合金的界面结合强度。粉末热挤压法制备的SiCp/2024铝基复合材料热处理后的断裂方式主要有3种：SiC颗粒断裂、SiC颗粒与基体合金的剥离和基体合金的韧性断裂，该复合材料的断裂机制为韧性断裂和脆性断裂共存的混合断裂。%SiCp/2024 aluminum matrix composites were fabricated by powder hot extrusion. Microstructures and mechanical properties of the composites after hot extrusion and heat treatment were studied. The fracture morphology and mechanism were also analyzed. The results show that SiC particles and the precipitated fine second phase particles disperse in the matrix uniformly and there are only a part of SiC particles clustering in local areas. The grains are elongated significantly along the extrusion direction and the long axis of the rigid SiC particles is paralleled to the extrusion direction as well, which shows a fibrous tissue during hot working. After the T6 heat treatment (490 ℃, 75 min+170℃, 8 h), the grains of the matrix are fine and the tensile strength can reach 470 MPa. The major precipitation strengthening phases is S′(Al2CuMg). The strength of the interface between SiC particles and 2024 matrix increases with increasing hot extrusion ratio. There are three types of fracture of the composite after heat treatment:the crack of SiC particles, the interface stripping between SiC and matrix, and the ductile fracture of the matrix. According to the microstructures, the fracture mechanism of the composite is the coexistence of ductile fracture and brittle fracture, which is a mixed fracture.
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