通过热压层合工艺制备 TC4f/L A91 复合材料,并对其复合界面显微组织和力学性能进行研究,为拓展M g-Li合金复合材料应用提供一定的理论与技术支持.分别用金相显微镜(Optical Microscopes,OM)、扫描电镜(Scanning Electron Microscope,SEM)观察复合材料的微观形貌,使用能谱仪(Energy Dispersive Spectrometer,EDS)检测元素分布情况、X射线衍射(X-ray Diffraction,XRD)分析复合材料的相组成,通过拉伸试验测试复合材料的力学性能.结果表明,TC4f/LA91复合材料界面具有扩散效应,基体中的主要元素Mg、Li、Al与增强体中的主要元素Ti、Al、V相互扩散,并随温度增加能够形成具有一定宽度(2～3 μm)且形状完整、轮廓清晰的扩散层,实现界面复合效果,界面处物相稳定,无新相产生.TC4f/LA91复合材料的抗拉强度对温度和增强体分数敏感,基本不随保温时间变化,有明显屈服现象.在 510℃保温 45 min工艺条件下、10 vol.%体积分数的抗拉强度为297 M Pa,相比LA91 基体抗拉强度增加50.76%,强化效果明显.在拉伸过程中,由于界面复合紧密,TC4 纤维未被拔出,其断口呈颈缩,LA91合金基体未发生明显开裂.
Study on preparation and microstructures properties of hot-pressed TC4f/LA91 composites
TC4f/LA91 composites were fabricated by hot-pressing lamination process in this study.The microstructures of the interfaces and mechanical properties of the composites were investigated to offer theoretical and technical insight for enhancing the application of Mg-Li alloy composites.The results indicate that the interface of TC4f/LA91 composites exhibits a diffusion effect.The primary components of Mg,Li,and Al are present in the LA91 alloy matrix while Ti,Al,and V are present in the TC4 fiber reinforcement,leading to diffusion between these elements.With temperature increasing,a diffusion layer with a certain width(2～3 μm),incomplete and clear boundary can be formed to realize the interfacial composites effect.The phases remain stable at the interface with no emergence of new phases.The microstructures of the TC4f/LA91 composites were observed by OM and SEM respectively.The elemental distribution was detected by EDS,and phase composition was analyzed by XRD.The mechanical properties of TC4f/LA91 composites were tested via tensile testing.The tensile strength of TC4f/LA91 composites is influenced by both temperature and reinforcement fraction,while remaining consistent with insulation time,and exhibits obvious yielding phenomenon.In the conditions of 45 minutes of heat preservation at 510℃,the tensile strength of TC4f/LA91 composites with 10 vol.%is 297 MPa,which increased 50.76%compared with the tensile strength of LA91 matrix,and demonstrates a highly effective strengthening effect.In the tensile process,due to the close interface composite,TC4 fibers were not pulled out and exhibited necking upon fracture,while no significant cracking was observed within the LA91 alloy matrix.
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