原位自生 Ti₅Si₃ 增强铝基复合材料的微观组织与力学性能调控机理

Regulation mechanism of microstructure and mechanical properties of in-situ synthesized Ti₅Si₃ reinforced aluminum matrix composites

摘要

原位法制备 Ti₅Si₃ 增强铝基复合材料（aluminum matrix composites，AMCs）增强相构成复杂、形成过程不易控制，难以实现复合材料微观组织与性能稳定调控。本工作通过设计原料组分配比及粉末冶金工艺参数，制备 Al-5Si- xTi₅Si₃（ x=0.8，2.0，3.2（质量分数/%））复合材料，深入研究增强相含量对复合材料微观组织及力学性能的影响。结果表明，Si 元素通过扩散及固溶析出在 Ti 颗粒周围偏聚，并与 Ti 发生互扩散反应生成 Ti₅Si₃ 颗粒。随着纳米尺度 TiSi 界面过渡层的形成，Ti₅Si₃/Al 非共格界面转变为 Ti₅Si₃/TiSi/Al 半共格/共格复合界面，有效促进增强相颗粒与铝基体间的界面结合。随着增强相含量增加，其微观结构逐渐由块状向纳米颗粒团簇转变并长大为纳米棒状，复合材料的晶粒尺寸得到显著细化。良好的界面结合实现了载荷通过界面的有效传递，促进增强相承载效果的发挥。在位错强化、细晶强化及载荷传递强化的协同作用下，Al-5Si-3.2Ti₅Si₃ 复合材料的屈服强度和抗拉强度分别达到 318 MPa 和 377 MPa，较基体分别提高 51.4% 和 42.8%，并保持良好的塑性。这些研究结果为高强韧 AMCs 的组织结构设计提供新方向，为该材料在航空航天等关键工程领域的应用提供数据支撑。

Abstract

Aiming at the bottleneck in in-situ synthesized Ti₅Si₃ reinforced aluminum matrix composites (AMCs)， where the complex constitution of reinforcements and poor controllability of formation process make it difficult to stably regulate the microstructure and properties of composites， Al-5Si- xTi₅Si₃ composites ( x=0.8， 2.0， 3.2 (mass fraction/%)) are fabricated by designing raw material proportions and powder metallurgy process parameters in this work. The effects of reinforcement content on the microstructure and mechanical properties of the composites are systematically investigated. The results show that Si segregates around Ti particles via diffusion and solid-solution precipitation，and interdiffusion reaction occurs between Si and Ti to form Ti₅Si₃ particles. With the formation of a nanoscale TiSi interfacial transition layer，the incoherent Ti₅Si₃/Al interface transforms into a semi-coherent/coherent composite Ti₅Si₃/TiSi/Al interface，which effectively improves the interfacial bonding between reinforcement particles and the Al matrix. As the reinforcement content increases，the microstructure of reinforcements gradually evolves from blocky morphology to nanoparticle clusters and further grows into nanorods，and the grain size of the composites is significantly refined. Sound interfacial bonding enables efficient load transfer across the interface and promotes the load-bearing capacity of reinforcements. Under the synergistic effect of dislocation strengthening，grain refinement strengthening and load transfer strengthening，the yield strength and tensile strength of the Al-5Si-3.2Ti₅Si₃ composite reach 318 MPa and 377 MPa，which are 51.4% and 42.8% higher than those of the matrix，respectively，while maintaining favorable ductility. These findings provide a new strategy for the microstructure design of high-strength and high-toughness AMCs，and offer an experimental foundation for the application of such materials in critical engineering fields such as aerospace.

关键词

铝基复合材料 / Ti₅Si₃ 增强相 / 粉末冶金 / 原位自生 / 力学性能

Key words

aluminum matrix composites / Ti₅Si₃ reinforcement / powder metallurgy / in-situ synthesis / mechanical property

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基金资助

国家自然科学基金(52671209，52201165)

航空科学基金(2023Z0530T6003)

中国博士后科学基金(2023MD744251)

西安市科技计划项目(24GXPT0001)

陕西省教育厅科研计划项目(24JS035)