真空吸渗挤压制备2D-C_f/Al复合材料的组织和性能研究

采用真空吸渗挤压工艺制备了二维碳纤维增强铝基(2D-Cf/Al)复合材料。在挤压力(比压)为60~90 MPa、真空度为10~30 k Pa、浸渗挤压温度为580~620℃、保压时间为60~120 s时,可以获得浸渗充分和成形质量良好的复合材料。微观组织观察分析表明,基体合金和碳纤维分布均匀,纤维无折断、漂移现象,无明显微观缺陷。对Cf/Al复合材料进行密度和拉伸性能测试,其密度比基体合金降低17.9%,抗拉强度提高100%。热处理实验表明,经过T6热处理,基体合金的组织得到改善,内部应力和缺陷得到有效控制和消除,抗拉强度提高41%,而碳纤维和基体合金热膨胀系数的差异会在复合材料内部产生不良应力,导致其拉伸性能没有提高反而下降16%。

Fabrication of 2D-Cf/Al Composite by an Extrusion Directly Following Vacuum Pressure Infiltration Technique and Its Microstructure and Properties

An extrusion directly following vacuum pressure infiltration technique was used to fabricate 2D-Cf/Al composite. When the specific pressure is 60~90 MPa, vacuum level is maintained at 10~30 kPa, squeeze infiltration temperature is 580~620 oC and keeping pressure time is 60~120 s, 2D-Cf/Al composite with ideal infiltration quality could be fabricated. Through microstructure observation, it is shown that the aluminum alloy is filled uniformly, and defects could be seldom found in composite. The experiment results indicate that the density of the composite is 17.9% lower than that of the matrix. Ultimate tensile strength of composite is satisfied, which is improved by 100% compared with that of matrix alloy. Heat treatment tests reveal the ultimate tensile strength is improved by 41%, because the microstructure is improved and the internal stress and defects are controlled effectively after heat treatment. On the contrary, the adverse stress would appear in the composite because of the difference of thermal expansion coefficient between carbon fiber and matrix alloy in the process of heat treatment, so the mechanical properties of the composite is decreased by 16%.