纳米晶复合孕育剂变质细化铝合金的强韧化机理及组织性能调控

Aluminum alloy with low density, good plasticity, excellent conductive and thermal conductivity and corrosion resistance is a kind of light metal material with excellent performance and wide application. With the development of aerospace and equipment manufacturing industry in recent years, the performance of existing aluminum alloys cannot meet its high demand. Although the high strength and high plasticity toughened aluminum alloy and Al matrix composites have great market space in China, the aluminum alloy is still not able to guarantee its high strength and toughness in composition design, fabrication and processing. These problems can be summed up as 1) the modification and refinement of the as cast microstructure of the aluminum alloy, 2) the size and distribution of the reinforcing phase, and 3) the key scientific problems of the strengthening and toughening mechanism of the matrix structure have not yet been well solved. The nanocrystalline AlN-TiN/Al-B-Ce composite inoculant was prepared based on thermodynamic calculation and composition design, and the grain of aluminum alloy matrix was refined. Through the research of the grain refinement mechanism, we can clarify toughening mechanism on aluminum alloy; through the optimization of centrifugal fast quenching effect on ceramic particle size and distribution, to achieve optimization and control of ceramic nanoparticles on microstructure and properties of aluminum alloy; Through the study on the relationship between microstructure and mechanical properties of aluminum alloy matrix refined by nanocrystalline composite inoculants and reinforced by ceramic nanoparticles, to provide a theoretical basis for the development of a new type of aluminum alloy and Al matrix composites with high strength and high toughness.

铝合金密度低、塑性好、具有优良的导电导热和抗蚀性，是一种性能优异应用广泛的轻金属材料。随着近年来航空航天及装备制造业的发展，现有铝合金的性能已不能满足其高端需求。尽管高强韧铝合金及铝基复合材料在我国的市场空间很大，但目前铝合金在成分设计、制备与加工方面仍不能保证其具有高强韧的组织和性能。这些问题可归结为1）铝合金铸态组织的变质细化、2）增强相的大小与分布、3）基体组织的强韧化机制几个关键科学问题尚未很好地解决。项目拟在热力学计算和成分设计基础上、制备纳米晶AlN-TiN/Al-B-Ce复合孕育剂，并用其变质细化铝合金基体晶粒。通过研究其变质细化机理阐明铝合金的强韧化机制;通过优化离心快淬对自生陶瓷颗粒尺寸和分布的影响，实现纳米增强相对铝基体晶内增强和性能调控；研究阐明纳米晶复合孕育剂变质细化、自生陶瓷颗粒增强铝合金的微观组织与其力学性能的关系，为研制高强韧铝合金及铝基复合材料提供理论依据。

近年来航空航天及装备制造业的发展，现有铝合金的性能已不能满足其高端需求。尽管高强韧铝合金及铝基复合材料在我国的市场空间很大，但目前铝合金在成分设计、制备与加工方面仍不能保证其具有高强韧的组织和性能。这些问题可归结为1）铝合金铸态组织的变质细化、2）增强相的大小与分布、3）基体组织的强韧化机制几个关键科学问题尚未很好地解决。项目针对以上几个关键科学问题，项目在纳米晶复合孕育剂变质细化系列铝合金的强韧化机理及组织性能调控研究方面开展了系统的基础研究如下：1）进行了系列纳米晶复合材料原位反应热力学和动力学研究；完成了AlN-TiN/Al复合材料的反应生成机制及对铝合金基体变质细化的研究。2）采用原位反应合成方法制备出了纳米晶NbB2+NbC/Al复合材料孕育剂并用于细化和增强2219铝合金；3）采用原位反应合成方法制备出了纳米晶CeB6/Al复合材料孕育剂并用于细化和增强Al-Cu-Mn和5083铝合金；4）用原位合成和熔体快淬方法制备了TiC-TiB2/Al孕育剂用于Al-Si 合金的变质细化和晶内增强。5）用Mo, Zr, Y及Al作为反应元素原位合成和熔体快淬方法制备了纳米晶Al12Mo-Al3Zr-Al3Y/Al复合孕育剂并用于Al-Cu-Mn铝合金的变质细化和强韧化； 6）用原位合成和离心快淬方法制备出了纳米晶VB2-AlN-Al4C3-VSi2/Al孕育剂并用于变质细化Al-12Si合金，优化了铝合金的铸态微观组织、显著提高了铝硅合金的力学性能。7）用原位合成和离心快淬方法制备出了纳米晶Al3Sc/Al复合孕育剂，并用于变质细化α-Al，并研究阐明了纳米晶Al3Sc/Al对α-Al变质细化机理及变质细化效果。8）通过粉末冶金+真空快淬工艺制备了TiC@TiN 核壳结构并用于变质细化Al-Zn-Mg-Cu合金，研究阐明了TiC@TiN变质细化7xxx铝合金的组织与性能之间的关系。.项目通过对比有无变质细化两种铸态组织与力学性能的对应关系与规律，系统研究阐明了系列纳米陶瓷颗粒可在基体合金熔体中形成大量纳米尺寸的异质核心的理论问题；揭示了纳米陶瓷颗粒晶内增强的形成机制，解决了孕育剂中陶瓷颗粒的大小与分布以及与基体润湿等科学问题。实现了纳米增强相对铝基体晶内增强和性能调控。